按降序排列字符串的程序-yiteyi-C++库

给定一个字符串，按降序排序。 例如：

null

Input : alkasinghOutput : snlkihgaa Input : nupursinghOutput : uusrpnnihg Input : geeksforgeeksOutput : ssrokkggfeeee

建议：请在“上解决” 实践 “首先，在讨论解决方案之前。

A. 简单解决方案 是使用库排序功能 std:：sort（）

C++

                         // CPP program to sort a string in descending                       
                         // order using library function                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         void                                     descOrder(string s)                       
                         {                       
                                                 sort(s.begin(), s.end(), greater<                                     char                                     >());                       
                         }                       
           
                         int                                     main()                       
                         {                       
                                                 string s =                                     "geeksforgeeks"                                     ;                       
                                                 descOrder(s);                                     // function call                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to sort a string in descending                       
                         // order using library function                       
                         import                                     java.util.*;                       
           
                         class                                     GFG                       
                         {                       
           
                                                 static                                     void                                     descOrder(                                     char                                     [] s)                       
                                                 {                       
                                                 Arrays.sort(s);                       
                                                 reverse(s);                       
                                                 }                       
           
                                                 static                                     void                                     reverse(                                     char                                     [] a)                       
                                                 {                       
                                                 int                                     i, n = a.length;                       
                                                 char                                     t;                       
                                                 for                                     (i =                                     0                                     ; i < n /                                     2                                     ; i++)                       
                                                 {                       
                                                 t = a[i];                       
                                                 a[i] = a[n - i -                                     1                                     ];                       
                                                 a[n - i -                                     1                                     ] = t;                       
                                                 }                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 char                                     [] s =                                     "geeksforgeeks"                                     .toCharArray();                       
                                                 descOrder(s);                                     // function call                       
                                                 System.out.println(String.valueOf(s));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by 29AjayKumar                       

python

                         # Python program to sort                       
                         # a string in descending                       
                         # order using library function                       
           
                         def                                     descOrder(s):                       
                                                 s.sort(reverse                                     =                                     True                                     )                       
                                                 str1                                     =                                     ''.join(s)                       
                                                 print                                     (str1)                       
           
                         def                                     main():                       
                                                 s                                     =                                     list                                     (                                     'geeksforgeeks'                                     )                       
                                   
                                                 # function call                       
                                                 descOrder(s)                       
           
                         if                                     __name__                                     =                                     =                                     "__main__"                                     :                       
                                                 main()                       
           
                         # This code is contributed by                       
                         # prabhat kumar singh                       

C#

                         // C# program to sort a string in descending                       
                         // order using library function                       
                         using                                     System;                       
                                   
                         class                                     GFG                       
                         {                       
                                   
                                                 static                                     void                                     descOrder(                                     char                                     [] s)                       
                                                 {                       
                                                 Array.Sort(s);                       
                                                 reverse(s);                       
                                                 }                       
                                   
                                                 static                                     void                                     reverse(                                     char                                     [] a)                       
                                                 {                       
                                                 int                                     i, n = a.Length;                       
                                                 char                                     t;                       
                                                 for                                     (i = 0; i < n / 2; i++)                       
                                                 {                       
                                                 t = a[i];                       
                                                 a[i] = a[n - i - 1];                       
                                                 a[n - i - 1] = t;                       
                                                 }                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main(String[] args)                       
                                                 {                       
                                                 char                                     [] s =                                     "geeksforgeeks"                                     .ToCharArray();                       
                                                 descOrder(s);                                     // function call                       
                                                 Console.WriteLine(String.Join(                                     ""                                     ,s));                       
                                                 }                       
                         }                       
           
                         // This code is contributed by Rajput-Ji                       

PHP

                         <?php                       
                         // PHP program to sort a string in descending                       
                         // order using library function                       
           
                         function                                     descOrder(                                     $s                                     )                       
                         {                       
                                                 $s                                     =                                     str_split                                     (                                     $s                                     );                       
                                                 rsort(                                     $s                                     );                       
                                                 echo                                     implode(                                     ''                                     ,                                     $s                                     );                       
                         }                       
           
                         // Driver Code                       
                         $s                                     =                                     "geeksforgeeks"                                     ;                       
                         descOrder(                                     $s                                     );                                     // function call                       
           
                         // This code is contributed by ita_c                       
                         ?>                       

Javascript

                         <script>                       
           
                                                 //  JavaScript program to sort                       
                                                 //  a string in descending                       
                                                 //  order using library function                       
           
                                                 function                                     descOrder(s) {                       
                                                 s.sort().reverse();                       
                                                 str1 = s.join(                                     ""                                     );                       
                                                 document.write(str1);                       
                                                 }                       
           
                                                 var                                     s =                                     "geeksforgeeks"                                     ;                       
                                                 s = s.split(                                     ""                                     );                       
                                   
                                                 // function call                       
                                                 descOrder(s);                       
                                   
                                                 </script>                       

输出：

 ssrokkggfeeee

时间复杂度为：O（n logn）一 有效的方法 首先要注意的是，总共只能有26个独特的字符。因此，我们可以将从“a”到“z”的所有字符的出现次数存储在散列数组中。散列数组的第一个索引将表示字符“a”，第二个索引将表示“b”，依此类推。最后，我们将简单地遍历散列数组，并打印从“z”到“a”的字符，这些字符在输入字符串中出现的次数。以下是上述理念的实施：

C++

                         // C++ program to sort a string of characters                       
                         // in descending order                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         const                                     int                                     MAX_CHAR = 26;                       
           
                         // function to print string in sorted order                       
                         void                                     sortString(string& str)                       
                         {                       
                                                 // Hash array to keep count of characters.                       
                                                 // Initially count of all charters is                       
                                                 // initialized to zero.                       
                                                 int                                     charCount[MAX_CHAR] = { 0 };                       
           
                                                 // Traverse string and increment                       
                                                 // count of characters                       
                                                 for                                     (                                     int                                     i = 0; i < str.length(); i++)                       
           
                                                 // 'a'-'a' will be 0, 'b'-'a' will be 1,                       
                                                 // so for location of character in count                       
                                                 // array we will do str[i]-'a'.                       
                                                 charCount[str[i] -                                     'a'                                     ]++;                       
           
                                                 // Traverse the hash array and print                       
                                                 // characters                       
                                                 for                                     (                                     int                                     i = MAX_CHAR - 1; i >= 0; i--)                       
                                                 for                                     (                                     int                                     j = 0; j < charCount[i]; j++)                       
                                                 cout << (                                     char                                     )(                                     'a'                                     + i);                       
                         }                       
           
                         // Driver program to test above function                       
                         int                                     main()                       
                         {                       
                                                 string s =                                     "alkasingh"                                     ;                       
                                                 sortString(s);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to sort a string of characters                       
                         // in descending order                       
           
                         class                                     GFG                       
                         {                       
           
                                                 static                                     int                                     MAX_CHAR =                                     26                                     ;                       
           
                                                 // function to print string in sorted order                       
                                                 static                                     void                                     sortString(String str)                       
                                                 {                       
                                   
                                                 // Hash array to keep count of characters.                       
                                                 // Initially count of all charters is                       
                                                 // initialized to zero.                       
                                                 int                                     charCount[] =                                     new                                     int                                     [MAX_CHAR];                       
           
                                                 // Traverse string and increment                       
                                                 // count of characters                       
                                                 // 'a'-'a' will be 0, 'b'-'a' will be 1,                       
                                                 for                                     (                                     int                                     i =                                     0                                     ; i < str.length(); i++)                       
                                                 {                       
                                   
                                                 // so for location of character in count                       
                                                 // array we will do str[i]-'a'.                       
                                                 charCount[str.charAt(i) -                                     'a'                                     ]++;                       
                                                 }                       
           
                                                 // Traverse the hash array and print                       
                                                 // characters                       
                                                 for                                     (                                     int                                     i = MAX_CHAR -                                     1                                     ; i >=                                     0                                     ; i--)                       
                                                 {                       
                                                 for                                     (                                     int                                     j =                                     0                                     ; j < charCount[i]; j++)                       
                                                 {                       
                                                 System.out.print((                                     char                                     ) (                                     'a'                                     + i));                       
                                                 }                       
                                                 }                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
                                                 String s =                                     "alkasingh"                                     ;                       
                                                 sortString(s);                       
                                                 }                       
                         }                       
           
                         // This code is contributed by 29AjayKumar                       

Python3

                         # Python program to sort a string of characters                       
                         # in descending order                       
           
                         MAX_CHAR                                     =                                     26                                     ;                       
           
                         # function to print string in sorted order                       
                         def                                     sortString(                                     str                                     ):                       
                                   
                                                 # Hash array to keep count of characters.                       
                                                 # Initially count of all charters is                       
                                                 # initialized to zero.                       
                                                 charCount                                     =                                     [                                     0                                     ]                                     *                                     MAX_CHAR;                       
           
                                                 # Traverse string and increment                       
                                                 # count of characters                       
                                                 for                                     i                                     in                                     range                                     (                                     len                                     (                                     str                                     )):                       
           
                                                 # 'a'-'a' will be 0, 'b'-'a' will be 1,                       
                                                 # so for location of character in count                       
                                                 # array we will do str[i]-'a'.                       
                                                 charCount[                                     ord                                     (                                     str                                     [i])                                     -                                     ord                                     (                                     'a'                                     )]                                     +                                     =                                     1                                     ;                       
           
                                                 # Traverse the hash array and print                       
                                                 # characters                       
                                                 for                                     i                                     in                                     range                                     (MAX_CHAR                                     -                                     1                                     ,                                     -                                     1                                     ,                                     -                                     1                                     ):                       
                                                 for                                     j                                     in                                     range                                     (charCount[i]):                       
                                                 print                                     (                                     chr                                     (                                     97                                     +                                     i),end                                     =                                     "");                       
           
                         # Driver program to test above function                       
                         s                                     =                                     "alkasingh"                                     ;                       
                         sortString(s);                       
           
                         # This code is contributed by Princi Singh                       

C#

                         // C# program to sort a string of characters                       
                         // in descending order                       
                         using                                     System;                       
           
                         class                                     GFG                       
                         {                       
                                                 static                                     int                                     MAX_CHAR = 26;                       
           
                                                 // function to print string in sorted order                       
                                                 static                                     void                                     sortString(String str)                       
                                                 {                       
                                   
                                                 // Hash array to keep count of characters.                       
                                                 // Initially count of all charters is                       
                                                 // initialized to zero.                       
                                                 int                                     []charCount =                                     new                                     int                                     [MAX_CHAR];                       
           
                                                 // Traverse string and increment                       
                                                 // count of characters                       
                                                 // 'a'-'a' will be 0, 'b'-'a' will be 1,                       
                                                 for                                     (                                     int                                     i = 0; i < str.Length; i++)                       
                                                 {                       
                                   
                                                 // so for location of character in                       
                                                 // count array we will do str[i]-'a'.                       
                                                 charCount[str[i] -                                     'a'                                     ]++;                       
                                                 }                       
           
                                                 // Traverse the hash array and print                       
                                                 // characters                       
                                                 for                                     (                                     int                                     i = MAX_CHAR - 1; i >= 0; i--)                       
                                                 {                       
                                                 for                                     (                                     int                                     j = 0; j < charCount[i]; j++)                       
                                                 {                       
                                                 Console.Write((                                     char                                     ) (                                     'a'                                     + i));                       
                                                 }                       
                                                 }                       
                                                 }                       
           
                                                 // Driver code                       
                                                 public                                     static                                     void                                     Main(String[] args)                       
                                                 {                       
                                                 String s =                                     "alkasingh"                                     ;                       
                                                 sortString(s);                       
                                                 }                       
                         }                       
           
                         // This code is contributed by PrinciRaj1992                       

Javascript

                         <script>                       
                         // Javascript program to sort a string of characters                       
                         // in descending order                       
                                                 let MAX_CHAR = 26;                       
                                   
                                                 // function to print string in sorted order                       
                                                 function                                     sortString(str)                       
                                                 {                       
                                   
                                                 // Hash array to keep count of characters.                       
                                                 // Initially count of all charters is                       
                                                 // initialized to zero.                       
                                                 let charCount =                                     new                                     Array(MAX_CHAR);                       
                                                 for                                     (let i = 0; i < charCount.length; i++)                       
                                                 {                       
                                                 charCount[i] = 0;                       
                                                 }                       
                                   
                                                 // Traverse string and increment                       
                                                 // count of characters                       
                                                 // 'a'-'a' will be 0, 'b'-'a' will be 1,                       
                                                 for                                     (let i = 0; i < str.length; i++)                       
                                                 {                       
                                   
                                                 // so for location of character in count                       
                                                 // array we will do str[i]-'a'.                       
                                                 charCount[str[i].charCodeAt(0) -                                     'a'                                     .charCodeAt(0)]++;                       
                                                 }                       
                                   
                                                 // Traverse the hash array and print                       
                                                 // characters                       
                                                 for                                     (let i = MAX_CHAR - 1; i >= 0; i--)                       
                                                 {                       
                                                 for                                     (let j = 0; j < charCount[i]; j++)                       
                                                 {                       
                                                 document.write(String.fromCharCode (                                     'a'                                     .charCodeAt(0) + i));                       
                                                 }                       
                                                 }                       
                                                 }                       
                                   
                                                 // Driver code                       
                                                 let s =                                     "alkasingh"                                     ;                       
                                                 sortString(s);                       
                                   
                                                 // This code is contributed by avanitrachhadiya2155                       
                         </script>                       

输出：

snlkihgaa

时间复杂性： O（n），其中n是输入字符串的长度。 辅助空间： O（1）。本文由 普拉巴特·库马尔·辛格 .如果你喜欢GeekSforgek，并想贡献自己的力量，你也可以使用写极客。组织或者把你的文章寄去评论-team@geeksforgeeks.org.看到你的文章出现在Geeksforgeks主页上，并帮助其他极客。如果您发现任何不正确的地方，或者您想分享有关上述主题的更多信息，请写下评论。

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