مسابقه ی آسان

Main.cpp

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#include <iostream>

using namespace std;

#define MAX 1000 
  
int multiply(int x, int res[], int res_size); 
  
void factorial(int n, int birth) 
{ 
    int res[MAX]; 
    int counter = 0;
  
    res[0] = 1; 
    int res_size = 1; 
  
    for (int x=2; x<=n; x++) 
        res_size = multiply(x, res, res_size); 
  
    for (int i=res_size-1; i>=0; i--) 
        if (res[i] == birth){counter++;}
        cout << counter;
} 
  
int multiply(int x, int res[], int res_size) 
{ 
    int carry = 0; 
  
    for (int i=0; i<res_size; i++) 
    { 
        int prod = res[i] * x + carry; 
  
        res[i] = prod % 10;   
  
        carry  = prod/10;     
    } 
  
    while (carry) 
    { 
        res[res_size] = carry%10; 
        carry = carry/10; 
        res_size++; 
    } 
    return res_size; 
} 

int main()
{
    int n, birth;
    
    cin >> n >> birth;
    
    factorial(n, birth);

    return 0;
}