字符串中最后一个单词的长度-yiteyi-C++库

给定由大写/小写字母和空格字符“”组成的字符串s，返回字符串中最后一个单词的长度。如果最后一个单词不存在，则返回0。

null

例如：

Input  : str = "Geeks For Geeks"Output : 5length(Geeks)= 5Input : str = "Start Coding Here"Output : 4length(Here) = 4Input  :  **Output : 0

建议：请在“上解决” 实践 “首先，在讨论解决方案之前。

方法1：迭代索引0中的字符串 如果我们从左到右迭代字符串，我们必须小心最后一个单词后面的空格。第一个单词前的空格很容易被忽略。但是，如果字符串末尾有空格，则很难检测最后一个单词的长度。这可以由修剪字符串前后的空格 .如果修改给定字符串受到限制，我们需要创建字符串的副本，并从中修剪空格。

C++

                         // C++ program for implementation of simple                       
                         // approach to find length of last word                       
                         #include<bits/stdc++.h>                       
                         #include <boost/algorithm/string.hpp>                       
                         using                                     namespace                                     std;                       
           
                         int                                     lengthOfLastWord(string a)                       
                         {                       
                                                 int                                     len = 0;                       
                                   
                                                 /* String a is 'final'-- can not be modified                       
                                                 So, create a copy and trim the spaces from                       
                                                 both sides */                       
                                                 string str(a);                       
                                                 boost::trim_right(str);                       
                                                 for                                     (                                     int                                     i = 0; i < str.length(); i++)                       
                                                 {                       
                                                 if                                     (str.at(i) ==                                     ' '                                     )                       
                                                 len = 0;                       
                                                 else                       
                                                 len++;                       
                                                 }                       
                                                 return                                     len;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 string input =                                     "Geeks For Geeks "                                     ;                       
                                                 cout <<                                     "The length of last word is "                       
                                                 << lengthOfLastWord(input);                       
                         }                       
           
                         // This code is contributed by Rajput-Ji                       

JAVA

                         // Java program for implementation of simple                       
                         // approach to find length of last word                       
                         public                                     class                                     GFG {                       
                                                 public                                     int                                     lengthOfLastWord(                                     final                                     String a)                       
                                                 {                       
                                                 int                                     len =                                     0                                     ;                       
           
                                                 /* String a is 'final'-- can not be modified                       
                                                 So, create a copy and trim the spaces from                       
                                                 both sides */                       
                                                 String x = a.trim();                       
           
                                                 for                                     (                                     int                                     i =                                     0                                     ; i < x.length(); i++) {                       
                                                 if                                     (x.charAt(i) ==                                     ' '                                     )                       
                                                 len =                                     0                                     ;                       
                                                 else                       
                                                 len++;                       
                                                 }                       
           
                                                 return                                     len;                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 String input =                                     "Geeks For Geeks  "                                     ;                       
                                                 GFG gfg =                                     new                                     GFG();                       
                                                 System.out.println(                                     "The length of last word is "                                     + gfg.lengthOfLastWord(input));                       
                                                 }                       
                         }                       

Python3

                         # Python3 program for implementation of simple                       
                         # approach to find length of last word                       
                         def                                     lengthOfLastWord(a):                       
                                                 l                                     =                                     0                       
           
                                                 # String a is 'final'-- can not be modified                       
                                                 # So, create a copy and trim the spaces from                       
                                                 # both sides                       
                                                 x                                     =                                     a.strip()                       
           
                                                 for                                     i                                     in                                     range                                     (                                     len                                     (x)):                       
                                                 if                                     x[i]                                     =                                     =                                     " "                                     :                       
                                                 l                                     =                                     0                       
                                                 else                                     :                       
                                                 l                                     +                                     =                                     1                       
                                                 return                                     l                       
           
                         # Driver code                       
                         if                                     __name__                                     =                                     =                                     "__main__"                                     :                       
                                                 inp                                     =                                     "Geeks For Geeks "                       
                                                 print                                     (                                     "The length of last word is"                                     ,                       
                                                 lengthOfLastWord(inp))                       
           
                         # This code is contributed by                       
                         # sanjeev2552                       

C#

                         // C# program for implementation of simple                       
                         // approach to find length of last word                       
                         using                                     System;                       
           
                         class                                     GFG {                       
           
                                                 public                                     virtual                                     int                                     lengthOfLastWord(                                     string                                     a)                       
                                                 {                       
                                                 int                                     len = 0;                       
           
                                                 // String a is 'final'-- can                       
                                                 // not be modified So, create                       
                                                 // a copy and trim the                       
                                                 // spaces from both sides                       
                                                 string                                     x = a.Trim();                       
           
                                                 for                                     (                                     int                                     i = 0; i < x.Length; i++) {                       
                                                 if                                     (x[i] ==                                     ' '                                     ) {                       
                                                 len = 0;                       
                                                 }                       
                                                 else                                     {                       
                                                 len++;                       
                                                 }                       
                                                 }                       
           
                                                 return                                     len;                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main(                                     string                                     [] args)                       
                                                 {                       
                                                 string                                     input =                                     "Geeks For Geeks "                                     ;                       
                                                 GFG gfg =                                     new                                     GFG();                       
                                                 Console.WriteLine(                                     "The length of last word is "                       
                                                 + gfg.lengthOfLastWord(input));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by shrikanth13                       

Javascript

                         <script>                       
           
                         // js program for implementation of simple                       
                         // approach to find length of last word                       
           
           
                         function                                     lengthOfLastWord(a)                       
                         {                       
                                                 let len = 0;                       
           
                                                 // String a is 'final'-- can                       
                                                 // not be modified So, create                       
                                                 // a copy and trim the                       
                                                 // spaces from both sides                       
                                                 x = a.trim();                       
           
                                                 for                                     (let i = 0; i < x.length; i++) {                       
                                                 if                                     (x[i] ==                                     ' '                                     ) {                       
                                                 len = 0;                       
                                                 }                       
                                                 else                                     {                       
                                                 len++;                       
                                                 }                       
                                                 }                       
           
                                                 return                                     len;                       
                         }                       
           
                         // Driver code                       
           
                         input =                                     "Geeks For Geeks "                                     ;                       
                         document.write(                                     "The length of last word is "                                     + lengthOfLastWord(input));                       
           
           
           
                         </script>                       

输出：

Length of the last word is 5

方法2：迭代最后一个索引中的字符串。 这个想法更有效，因为我们可以很容易地忽略上一个的空间。这个想法是，当你遇到最后一个字母的第一个字母时，开始增加计数，当你遇到这些字母后面的空格时，停止计数。

C++

                         // CPP program for implementation of efficient                       
                         // approach to find length of last word                       
                         #include <bits/stdc++.h>                       
                         #include <iostream>                       
                         using                                     namespace                                     std;                       
           
                         int                                     length(string str)                       
                         {                       
                                                 int                                     count = 0;                       
                                                 bool                                     flag =                                     false                                     ;                       
                                                 for                                     (                                     int                                     i = str.length() - 1; i >= 0; i--) {                       
                                                 // Once the first character from last                       
                                                 // is encountered, set char_flag to true.                       
                                                 if                                     ((str[i] >=                                     'a'                                     && str[i] <=                                     'z'                                     ) || (str[i] >=                                     'A'                                     && str[i] <=                                     'Z'                                     )) {                       
                                                 flag =                                     true                                     ;                       
                                                 count++;                       
                                                 }                       
                                                 // When the first space after the                       
                                                 // characters (from the last) is                       
                                                 // encountered, return the length                       
                                                 // of the last word                       
                                                 else                                     {                       
                                                 if                                     (flag ==                                     true                                     )                       
                                                 return                                     count;                       
                                                 }                       
                                                 }                       
                                                 return                                     count;                       
                         }                       
           
                         // Driver code                       
                         int                                     main()                       
                         {                       
                                                 string str =                                     "Geeks for Geeks"                                     ;                       
                                                 cout <<                                     "The length of last word is "                                     << length(str);                       
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by rahulkumawat2107                       

JAVA

                         // Java program for implementation of efficient                       
                         // approach to find length of last word                       
                         public                                     class                                     GFG {                       
                                                 public                                     int                                     lengthOfLastWord(                                     final                                     String a)                       
                                                 {                       
                                                 boolean                                     char_flag =                                     false                                     ;                       
                                                 int                                     len =                                     0                                     ;                       
                                                 for                                     (                                     int                                     i = a.length() -                                     1                                     ; i >=                                     0                                     ; i--) {                       
                                                 if                                     (Character.isLetter(a.charAt(i))) {                       
                                                 // Once the first character from last                       
                                                 // is encountered, set char_flag to true.                       
                                                 char_flag =                                     true                                     ;                       
                                                 len++;                       
                                                 }                       
                                                 else                                     {                       
                                                 // When the first space after the characters                       
                                                 // (from the last) is encountered, return the                       
                                                 // length of the last word                       
                                                 if                                     (char_flag ==                                     true                                     )                       
                                                 return                                     len;                       
                                                 }                       
                                                 }                       
                                                 return                                     len;                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 String input =                                     "Geeks For Geeks  "                                     ;                       
                                                 GFG gfg =                                     new                                     GFG();                       
                                                 System.out.println(                                     "The length of last word is "                                     + gfg.lengthOfLastWord(input));                       
                                                 }                       
                         }                       

Python3

                         # Python3 program for implementation of efficient                       
                         # approach to find length of last word                       
                         def                                     length(                                     str                                     ):                       
           
                                                 count                                     =                                     0                                     ;                       
                                                 flag                                     =                                     False                                     ;                       
                                                 length                                     =                                     len                                     (                                     str                                     )                                     -                                     1                                     ;                       
                                                 while                                     (length !                                     =                                     0                                     ):                       
                                                 if                                     (                                     str                                     [length]                                     =                                     =                                     ' '                                     ):                       
                                                 return                                     count;                       
                                                 else                                     :                       
                                                 count                                     +                                     =                                     1                                     ;                       
                                                 length                                     -                                     =                                     1                                     ;                       
                                                 return                                     count;                       
           
                         # Driver code                       
                         str                                     =                                     "Geeks for Geeks"                                     ;                       
                         print                                     (                                     "The length of last word is"                                     ,                       
                                                 length(                                     str                                     ));                       
           
                         # This code is contributed by Rajput Ji                       

C#

                         // C# program for implementation of efficient                       
                         // approach to find length of last word                       
                         using                                     System;                       
           
                         class                                     GFG {                       
           
                                                 public                                     virtual                                     int                                     lengthOfLastWord(                                     string                                     a)                       
                                                 {                       
                                                 bool                                     char_flag =                                     false                                     ;                       
                                                 int                                     len = 0;                       
                                                 for                                     (                                     int                                     i = a.Length - 1; i >= 0; i--) {                       
                                                 if                                     (                                     char                                     .IsLetter(a[i])) {                       
                                                 // Once the first character from last                       
                                                 // is encountered, set char_flag to true.                       
                                                 char_flag =                                     true                                     ;                       
                                                 len++;                       
                                                 }                       
                                                 else                                     {                       
                                                 // When the first space after the                       
                                                 // characters (from the last) is                       
                                                 // encountered, return the length                       
                                                 // of the last word                       
                                                 if                                     (char_flag ==                                     true                                     ) {                       
                                                 return                                     len;                       
                                                 }                       
                                                 }                       
                                                 }                       
                                                 return                                     len;                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main(                                     string                                     [] args)                       
                                                 {                       
                                                 string                                     input =                                     "Geeks For Geeks "                                     ;                       
                                                 GFG gfg =                                     new                                     GFG();                       
                                                 Console.WriteLine(                                     "The length of last word is "                                     + gfg.lengthOfLastWord(input));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Shrikant13                       

PHP

                         <?php                       
                         // PHP program for implementation of efficient                       
                         // approach to find length of last word                       
           
                         function                                     length(                                     $str                                     )                       
                         {                       
                                                 $count                                     = 0;                       
                                                 $flag                                     = false;                       
                                                 for                                     (                                     $i                                     =                                     strlen                                     (                                     $str                                     )-1 ;                                     $i                                     >=0 ;                                     $i                                     --)                       
                                                 {                       
                                                 // Once the first character from last                       
                                                 // is encountered, set char_flag to true.                       
                                                 if                                     ( (                                     $str                                     [                                     $i                                     ] >=                                     'a'                                     &&                                     $str                                     [                                     $i                                     ]<=                                     'z'                                     ) ||                       
                                                 (                                     $str                                     [                                     $i                                     ] >=                                     'A'                                     &&                                     $str                                     [                                     $i                                     ]<=                                     'Z'                                     ))                       
                                                 {                       
                                                 $flag                                     = true;                       
                                                 $count                                     ++;                       
                                                 }                       
                                   
                                                 // When the first space after the                       
                                                 // characters (from the last) is                       
                                                 // encountered, return the length                       
                                                 // of the last word                       
                                                 else                       
                                                 {                       
                                                 if                                     (                                     $flag                                     == true)                       
                                                 return                                     $count                                     ;                       
                                                 }                       
                                   
                                                 }                       
                                                 return                                     $count                                     ;                       
                         }                       
           
                         // Driver code                       
                         $str                                     =                                     "Geeks for Geeks"                                     ;                       
                         echo                                     "The length of last word is "                                     , length(                                     $str                                     );                       
           
                         // This code is contributed by ajit.                       
                         ?>                       

输出：

Length of the last word is 5

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方法#3：使用split（）和list

因为一个句子中的所有单词都用空格隔开。
我们必须用空格分隔句子 split（）。
我们将所有单词按空格分割，并将它们存储在一个列表中。
打印列表中最后一个单词的长度。

以下是实施情况：

Python3

                         # Python3 program for implementation of efficient                       
                         # approach to find length of last word                       
           
           
                         def                                     length(                                     str                                     ):                       
                                                 # Split by space and converting                       
                                                 # String to list and                       
                                                 lis                                     =                                     list                                     (                                     str                                     .split(                                     " "                                     ))                       
                                                 return                                     len                                     (lis[                                     -                                     1                                     ])                       
           
           
                         # Driver code                       
                         str                                     =                                     "Geeks for Geeks"                       
                         print                                     (                                     "The length of last word is"                                     ,                       
                                                 length(                                     str                                     ))                       
           
                         # This code is contributed by vikkycirus                       

Javascript

                         <script>                       
           
                         // Javascript program for implementation                       
                         // of efficient approach to find length                       
                         // of last word                       
                         function                                     length(str)                       
                         {                       
                                   
                                                 // Split by space and converting                       
                                                 // String to list and                       
                                                 var                                     lis = str.split(                                     " "                                     )                       
                                                 return                                     lis[lis.length - 1].length;                       
                         }                       
           
                         // Driver code                       
                         var                                     str =                                     "Geeks for Geeks"                       
                         document.write(                                     "The length of last word is "                                     +                       
                                                 length(str));                       
           
                         // This code is contributed by bunnyram19                       
           
                         </script>                       

输出：

Length of the last word is 5

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