324 - Factorial Frequencies

Problem Link : https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=260

Solution Idea : have to calculate factorial of n and then iterate through it and find values.

Solution :

#include<bits/stdc++.h>
#define ll long long
#define MAX 800

using namespace std;

 ll int res[MAX];
ll int a[10];
ll int multiply(ll int x,ll int res_size);

void factorial(ll int n)
{


    res[0] = 1;
    ll int res_size = 1;

    for (ll int x=2; x<=n; x++)
        res_size = multiply(x, res_size);

    for (ll int i=res_size-1; i>=0; i--)
        a[res[i]]++;
}

ll int multiply(ll int x,ll int res_size)
{
   ll int carry = 0;

       for (ll int i=0; i<res_size; i++)
    {
        ll 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()
{

    ll int n;

  while(scanf("%lld",&n) and n)
    {
        memset(res,0,sizeof(res));
        memset(a,0,sizeof(a));

          factorial(n);

          printf("%lld! --\n",n);

          for(ll int i=0;i<=9;i++)
          {
             if(i!=4 and i!=9) printf("(%lld)    %lld    ",i,a[i]);
             else printf("(%lld)    %lld\n",i,a[i]);
          }
    }

}