如何计算大数的mod？

给定一个大数字“ num”表示为字符串和一个整数x，请找到“ num％x”或“ num mod x”的值。预期输出为整数。

例子 ：

Input:  num = "12316767678678",  a = 10
Output: num (mod a) ≡ 8

这个想法是一一处理所有数字并使用xy(mod a)≡((x(mod a)* y)(mod a))的属性。下面是实现。

感谢utkarsh111建议以下解决方案。

C++

// C++ program to compute mod of a big number represented
// as string
#include
using namespace std;
 
// Function to compute num (mod a)
int mod(string num, int a)
{
    // Initialize result
    int res = 0;
 
    // One by one process all digits of 'num'
    for (int i = 0; i < num.length(); i++)
         res = (res*10 + (int)num[i] - '0') %a;
 
    return res;
}
 
// Driver program
int main()
{
    string num = "12316767678678";
    cout << mod(num, 10);
    return 0;
}

Java

// Java program to compute mod of a big
// number represented as string
import java.io.*;
 
class GFG {
     
    // Function to compute num (mod a)
    static int mod(String num, int a)
    {
         
        // Initialize result
        int res = 0;
 
        // One by one process all digits of 'num'
        for (int i = 0; i < num.length(); i++)
            res = (res * 10 + (int)num.charAt(i)
                                     - '0') % a;
 
        return res;
    }
 
    // Driver program
    public static void main(String[] args)
    {
         
        String num = "12316767678678";
         
        System.out.println(mod(num, 10));
    }
}
 
// This code is contributed by vt_m.

Python3

# program to compute mod of a big number
# represented as string
 
# Function to compute num (mod a)
def mod(num, a):
     
    # Initialize result
    res = 0
 
    # One by one process all digits
    # of 'num'
    for i in range(0, len(num)):
        res = (res * 10 + int(num[i])) % a;
 
    return res
 
# Driver program
num = "12316767678678";
print(mod(num, 10))
 
# This code is contributed by Sam007

C#

// C# program to compute mod of a big
// number represented as string
using System;
 
public class GFG
{
     
    // Function to compute num (mod a)
    static int mod(String num, int a)
    {
         
        // Initialize result
        int res = 0;
 
        // One by one process all
        // digits of 'num'
        for (int i = 0; i < num.Length; i++)
            res = (res * 10 + (int)num[i]-
                   '0') % a;
 
        return res;
    }
 
    // Driver code
    public static void Main()
    {
        String num = "12316767678678";
         
        Console.WriteLine(mod(num, 10));
    }
}
 
// This code is contributed by Sam007

Javascript

 
// Javascript program to compute mod
// of a big number represented
// as string
 
// Function to compute num (mod a)
function mod(num, a)
{
     
    // Initialize result
    let res = 0;
 
    // One by one process
    // all digits of 'num'
    for(let i = 0; i < num.length; i++)
        res = (res * 10 +
            num[i] - '0') % a;
 
    return res;
}
 
// Driver Code
let num = "12316767678678";
 
document.write(mod(num, 10));
 
// This code is contributed by _saurabh_jaiswal
 

输出 ：

8