JavaScript ES2015：块范围-yiteyi-C++库

给定一个数字 D ，表示正整数的位数。求至少有一个零的正整数（由d个数字组成）的总数。例如：

null

Input : d = 1Output : 0There's no natural number of 1 digit thatcontains a zero.Input : d = 2Output : 9The numbers are, 10, 20, 30, 40, 50, 60,                  70, 80 and 90.

我们强烈建议您在继续解决方案之前单击此处并进行练习。

一个简单的解决方案是遍历所有d位正数。对于每个数字，遍历其数字，如果有任何0位，则递增计数（类似于这 ). 以下是一些观察结果：

正好有d个数字。
最重要位置的数字不能为零（不允许前导零）。
除最重要的位置外，所有其他位置都可以包含零。

digits

考虑到以上几点，我们来计算d位数字的总数：

We can place any of {1, 2, ... 9} in D1Hence D1 can be filled in 9 ways.Apart from D1 all the other places can be  10 ways. (we can place 0 as well)Hence the total numbers having d digits can be given as: Total =  9*10^d-1Now, let's find the numbers having d digits, thatdon't contain zero at any place. In this case, all the places can be filled in 9 ways.Hence count of such numbers is given by:Non_Zero = 9^dNow the count of numbers having at least one zero can be obtained by subtracting Non_Zero from Total.Hence Answer would be given by:9*(10^{d-1 - 9d-1)}

下面是同样的程序。

C++

                         //C++ program to find the count of positive integer of a                       
                         // given number of digits that contain atleast one zero                       
                         #include<bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         // Returns count of 'd' digit integers have 0 as a digit                       
                         int                                     findCount(                                     int                                     d)                       
                         {                       
                                                 return                                     9*(                                     pow                                     (10,d-1) -                                     pow                                     (9,d-1));                       
                         }                       
           
                         // Driver Code                       
                         int                                     main()                       
                         {                       
                                                 int                                     d = 1;                       
                                                 cout << findCount(d) << endl;                       
           
                                                 d = 2;                       
                                                 cout << findCount(d) << endl;                       
           
                                                 d = 4;                       
                                                 cout << findCount(d) << endl;                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to find the count                       
                         // of positive integer of a                       
                         // given number of digits                       
                         // that contain atleast one zero                       
                         import                                     java.io.*;                       
           
                         class                                     GFG {                       
                                   
                                                 // Returns count of 'd' digit                       
                                                 // integers have 0 as a digit                       
                                                 static                                     int                                     findCount(                                     int                                     d)                       
                                                 {                       
                                                 return                                     9                                     * ((                                     int                                     )(Math.pow(                                     10                                     , d -                                     1                                     ))                       
                                                 - (                                     int                                     )(Math.pow(                                     9                                     , d -                                     1                                     )));                       
                                                 }                       
                                   
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     main(String args[])                       
                                                 {                       
                                                 int                                     d =                                     1                                     ;                       
                                                 System.out.println(findCount(d));                       
                                   
                                                 d =                                     2                                     ;                       
                                                 System.out.println(findCount(d));                       
                                   
                                                 d =                                     4                                     ;                       
                                                 System.out.println(findCount(d));                       
                                   
                                                 }                       
                         }                       
           
                         // This code is contributed by Nikita Tiwari.                       

Python3

                         # Python 3 program to find the                       
                         # count of positive integer of a                       
                         # given number of digits that                       
                         # contain atleast one zero                       
                         import                                     math                       
           
                         # Returns count of 'd' digit                       
                         # integers have 0 as a digit                       
                         def                                     findCount(d) :                       
                                                 return                                     9                                     *                                     ((                                     int                                     )(math.                                     pow                                     (                                     10                                     ,d                                     -                                     1                                     ))                                     -                                     (                                     int                                     )(math.                                     pow                                     (                                     9                                     ,d                                     -                                     1                                     )));                       
           
           
                         # Driver Code                       
                         d                                     =                                     1                       
                         print                                     (findCount(d))                       
                                   
                         d                                     =                                     2                       
                         print                                     (findCount(d))                       
           
                         d                                     =                                     4                       
                         print                                     (findCount(d))                       
           
           
                         # This code is contributed by Nikita Tiwari.                       

C#

                         // C# program to find the count                       
                         // of positive integer of a                       
                         // given number of digits                       
                         // that contain atleast one zero.                       
                         using                                     System;                       
           
                         class                                     GFG {                       
                                   
                                                 // Returns count of 'd' digit                       
                                                 // integers have 0 as a digit                       
                                                 static                                     int                                     findCount(                                     int                                     d)                       
                                                 {                       
                                                 return                                     9 * ((                                     int                                     )(Math.Pow(10, d - 1))                       
                                                 - (                                     int                                     )(Math.Pow(9, d - 1)));                       
                                                 }                       
                                   
                                                 // Driver Code                       
                                                 public                                     static                                     void                                     Main()                       
                                                 {                       
                                                 int                                     d = 1;                       
                                                 Console.WriteLine(findCount(d));                       
                                   
                                                 d = 2;                       
                                                 Console.WriteLine(findCount(d));                       
                                   
                                                 d = 4;                       
                                                 Console.WriteLine(findCount(d));                       
                                   
                                                 }                       
                         }                       
           
                         // This code is contributed by nitin mittal.                       

PHP

                         <?php                       
                         // PHP program to find the count                       
                         // of positive integer of a given                       
                         // number of digits that contain                       
                         // atleast one zero                       
           
                         // Returns count of 'd' digit                       
                         // integers have 0 as a digit                       
                         function                                     findCount(                                     $d                                     )                       
                         {                       
                                                 return                                     9 * (pow(10,                                     $d                                     - 1) -                       
                                                 pow(9,                                     $d                                     - 1));                       
                         }                       
           
                         // Driver Code                       
                         {                       
                                                 $d                                     = 1;                       
                                                 echo                                     findCount(                                     $d                                     ),                                     ""                                     ;                       
           
                                                 $d                                     = 2;                       
                                                 echo                                     findCount(                                     $d                                     ),                                     ""                                     ;                       
           
                                                 $d                                     = 4;                       
                                                 echo                                     findCount(                                     $d                                     ),                                     ""                                     ;                       
                                                 return                                     0;                       
                         }                       
           
                         // This code is contributed by nitin mittal                       
                         ?>                       

Javascript

                         <script>                       
           
                         // JavaScript program to find the count                       
                         // of positive integer of a                       
                         // given number of digits                       
                         // that contain atleast one zero                       
           
                                                 // Returns count of 'd' digit                       
                                                 // integers have 0 as a digit                       
                                                 function                                     findCount(d)                       
                                                 {                       
                                                 return                                     9 * ((Math.pow(10, d - 1))                       
                                                 - (Math.pow(9, d - 1)));                       
                                                 }                       
           
                         // Driver Code                       
           
                                                 let d = 1;                       
                                                 document.write(findCount(d) +                                     "<br/>"                                     );                       
                                   
                                                 d = 2;                       
                                                 document.write(findCount(d) +                                     "<br/>"                                     );                       
                                   
                                                 d = 4;                       
                                                 document.write(findCount(d) +                                     "<br/>"                                     );                       
                                   
                                                 // This code is contributed by target_2.                       
                         </script>                       

输出：

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