UVa - 623 ( 500 ! Solution ) [ With Algorithm ]

Tip : Hi there . So 500! Isn't that big ? Yes it is . But isn't it Hard? No simple. Just Follow the Algorithm . For help scroll down .

Algorithm :

1. For finding out the factorial of N ( any natural number ) we have to multiply the numbers from from 1 to N. That 1 x 2 x 3 x 4 x....x N.

2. As the number is very Big we have to multiply all the numbers before and including N and store the result in an array. For this we multiply all the number before and including N with the current multiplied result that is the result of all N-1 for current N.( one character at a time dividing by 10 and at last we have some remainder )

3. After that every time we have to put the remainder ( one character at a time ) into the array. (At this time the Array size will increase. )

=> Sub tip : You can optimize it by using string operation and its upto you .

Code :

#include<bits/stdc++.h>

using namespace std;

int main()

{

    int t;

    int a[3000];

    int n,i,j,temp,m,x;

    while(scanf("%d",&n)==1)

    {

       a[0]=1;

       m=1;

       temp = 0;

       for(i=1;i<=n;i++)

       {

            for(j=0;j<m;j++)

            {

               x = a[j]*i+temp;

               a[j]=x%10;

               temp = x/10;

            }

             while(temp>0)

             {

               a[m]=temp%10;

               temp = temp/10;

               m++;

             }

      }

      printf("%d!\n",n);

      for(i=m-1;i>=0;i--)

      printf("%d",a[i]);

      printf("\n");

    }

    return 0;

}

=> Questions ?? Leave a Comment .