给定分数中第一个数字的出现-yiteyi-C++库

给定三个整数a、b和c，找出a/b中小数点后第一个出现的c。如果不存在，请打印-1。例如：

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Input : a = 2 b = 3 c = 6 Output : 1 Explanation: 0.666666.. so 6 occurs at first place of a/b after decimal pointInput : a = 1 b = 4 c = 5 Output : 2 Explanation: 1 / 4 = 0.25 which gives 5's positionto be 2.

推荐：请尝试你的方法 {IDE} 首先，在进入解决方案之前。

A. 幼稚的方法 将执行除法并保留小数部分，迭代并检查给定的数字是否存在。当进行2/3这样的除法时，这将不能很好地工作，因为它产生0.666，但在编程语言中，它会将其四舍五入到0.666667，因此我们也会得到一个7，这在原始a/b中不存在一 有效的方法 将是数学上的一个，如果我们每次用a乘以b，再乘以10，我们每次都会得到小数点后的整数。所需的调制数为b，因为小数点后最多有b个整数。因此，我们将其与c进行比较，如果它存在，则得到我们想要的值。以下是上述方法的实施情况：

C++

                         // CPP program to find first occurrence                       
                         // of c in a/b                       
                         #include <bits/stdc++.h>                       
                         using                                     namespace                                     std;                       
           
                         // function to print the first digit                       
                         int                                     first(                                     int                                     a,                                     int                                     b,                                     int                                     c)                       
                         {                       
                                                 // reduce the number to its mod                       
                                                 a %= b;                       
           
                                                 // traverse for every decimal places                       
                                                 for                                     (                                     int                                     i = 1; i <= b; i++)                       
                                                 {                       
                                                 // get every fraction places                       
                                                 // when (a*10/b)/c                       
                                                 a = a * 10;                       
                                   
                                                 // check if it is equal to                       
                                                 // the required integer                       
                                                 if                                     (a / b == c)                       
                                                 return                                     i;                       
                                   
                                                 // mod the number                       
                                                 a %= b;                       
                                                 }                       
                                                 return                                     -1;                       
                         }                       
           
                         // driver program to test the above function                       
                         int                                     main()                       
                         {                       
                                                 int                                     a = 1, b = 4, c = 5;                       
                                                 cout << first(a, b, c);                       
                                                 return                                     0;                       
                         }                       

JAVA

                         // Java program to find first occurrence                       
                         // of c in a/b                       
                         import                                     java.util.*;                       
                         import                                     java.lang.*;                       
           
                         public                                     class                                     GfG{                       
                                                 // Function to print the first digit                       
                                                 public                                     static                                     int                                     first(                                     int                                     a,                                     int                                     b,                                     int                                     c)                       
                                                 {                       
                                                 // Reduce the number to its mod                       
                                                 a %= b;                       
           
                                                 // Traverse for every decimal places                       
                                                 for                                     (                                     int                                     i =                                     1                                     ; i <= b; i++)                       
                                                 {                       
                                                 // Get every fraction places                       
                                                 // when (a*10/b)/c                       
                                                 a = a *                                     10                                     ;                       
                                   
                                                 // Check if it is equal to                       
                                                 // the required integer                       
                                                 if                                     (a / b == c)                       
                                                 return                                     i;                       
                                   
                                                 // Mod the number                       
                                                 a %= b;                       
                                                 }                       
                                                 return                                     -                                     1                                     ;                       
                                                 }                       
                                   
                                                 // Driver function                       
                                                 public                                     static                                     void                                     main(String argc[]){                       
                                                 int                                     a =                                     1                                     , b =                                     4                                     , c =                                     5                                     ;                       
                                                 System.out.println(first(a, b, c));                       
                                                 }                       
                                   
                         }                       
                         /* This code is contributed by Sagar Shukla */                       

Python3

                         # Python3 program to find first occurrence                       
                         # of c in a/b                       
           
                         # function to print the first digit                       
                         def                                     first( a , b , c ):                       
           
                                                 # reduce the number to its mod                       
                                                 a                                     %                                     =                                     b                       
                                   
                                                 # traverse for every decimal places                       
                                                 for                                     i                                     in                                     range                                     (                                     1                                     , b                                     +                                     1                                     ):                       
           
                                                 # get every fraction places                       
                                                 # when (a*10/b)/c                       
                                                 a                                     =                                     a                                     *                                     10                       
           
                                                 # check if it is equal to                       
                                                 # the required integer                       
                                                 if                                     int                                     (a                                     /                                     b)                                     =                                     =                                     c:                       
                                                 return                                     i                       
                                   
                                                 # mod the number                       
                                                 a                                     %                                     =                                     b                       
                                   
                                                 return                                     -                                     1                       
           
                         # driver code to test the above function                       
                         a                                     =                                     1                       
                         b                                     =                                     4                       
                         c                                     =                                     5                       
                         print                                     (first(a, b, c))                       
           
                         # This code is contributed by "Sharad_Bhardwaj".                       

C#

                         // C# program to find first occurrence                       
                         // of c in a/b                       
                         using                                     System;                       
           
                         public                                     class                                     GfG{                       
                                   
                                                 // Function to print the first digit                       
                                                 public                                     static                                     int                                     first(                                     int                                     a,                                     int                                     b,                                     int                                     c)                       
                                                 {                       
           
                                                 // Reduce the number to its mod                       
                                                 a %= b;                       
           
                                                 // Traverse for every decimal places                       
                                                 for                                     (                                     int                                     i = 1; i <= b; i++)                       
                                                 {                       
           
                                                 // Get every fraction places                       
                                                 // when (a*10/b)/c                       
                                                 a = a * 10;                       
                                   
                                                 // Check if it is equal to                       
                                                 // the required integer                       
                                                 if                                     (a / b == c)                       
                                                 return                                     i;                       
                                   
                                                 // Mod the number                       
                                                 a %= b;                       
                                                 }                       
           
                                                 return                                     -1;                       
                                                 }                       
                                   
                                                 // Driver function                       
                                                 public                                     static                                     void                                     Main() {                       
                                   
                                                 int                                     a = 1, b = 4, c = 5;                       
                                   
                                                 Console.WriteLine(first(a, b, c));                       
                                                 }                       
                         }                       
           
                         /* This code is contributed by vt_m */                       

PHP

                         <?php                       
                         // PHP program to find first                       
                         // occurrence of c in a/b                       
           
                         // function to print                       
                         // the first digit                       
                         function                                     first(                                     $a                                     ,                                     $b                                     ,                                     $c                                     )                       
                         {                       
                                   
                                                 // reduce the number                       
                                                 // to its mod                       
                                                 $a                                     %=                                     $b                                     ;                       
           
                                                 // traverse for every                       
                                                 // decimal places                       
                                                 for                                     (                                     $i                                     = 1;                                     $i                                     <=                                     $b                                     ;                                     $i                                     ++)                       
                                                 {                       
                                   
                                                 // get every fraction places                       
                                                 // when (a*10/b)/c                       
                                                 $a                                     =                                     $a                                     * 10;                       
                                   
                                                 // check if it is equal to                       
                                                 // the required integer                       
                                                 if                                     (                                     $a                                     /                                     $b                                     ==                                     $c                                     )                       
                                                 return                                     $i                                     ;                       
                                   
                                                 // mod the number                       
                                                 $a                                     %=                                     $b                                     ;                       
                                                 }                       
                                                 return                                     -1;                       
                         }                       
           
                                                 // Driver Code                       
                                                 $a                                     = 1;                                     $b                                     = 4;                                     $c                                     = 5;                       
                                                 echo                                     first(                                     $a                                     ,                                     $b                                     ,                                     $c                                     );                       
           
                         // This code is contributed by anuj_67.                       
                         ?>                       

Javascript

                         <script>                       
           
                         // JavaScript program to find first occurrence                       
                         // of c in a/b                       
           
                                                 // Function to print the first digit                       
                                                 function                                     first(a, b, c)                       
                                                 {                       
                                                 // Reduce the number to its mod                       
                                                 a %= b;                       
                                   
                                                 // Traverse for every decimal places                       
                                                 for                                     (let i = 1; i <= b; i++)                       
                                                 {                       
                                                 // Get every fraction places                       
                                                 // when (a*10/b)/c                       
                                                 a = a * 10;                       
                                   
                                                 // Check if it is equal to                       
                                                 // the required integer                       
                                                 if                                     (a / b == c)                       
                                                 return                                     i;                       
                                   
                                                 // Mod the number                       
                                                 a %= b;                       
                                                 }                       
                                                 return                                     -1;                       
                                                 }                       
           
                         // Driver Code                       
           
                                                 let a = 1, b = 4, c = 5;                       
                                                 document.write(first(a, b, c));                       
           
                         // This code is contributed by chinmoy1997pal.                       
                         </script>                       

输出：

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