Perfect Number (Solution to week 1 Assignment)

Write a program to find whether a given number (say x) is a “perfect number” or not.

Definition of Perfect number:

A perfect number is a positive integer that is equal to the sum of its proper positive divisors excluding the number itself. By this definition, 1 is not a perfect number.

Explanation:

Take number 6.

Proper positive divisors of 6 is 1,2,3 and their sum is 1+2+3=6.
So, 6 is a perfect number.

Constraint:
1<=x<=1,000,000

Input: A single positive number  x

Output:
yes if given number x is a perfect number

no if given number x is not a perfect number

Example 1:

Input: 6

Output: yes

Example 2:

Input: 7

Output: no


Solution -:

#include<stdio.h>
int fact();int s=0,i;
int main()
{int n,d;
  scanf("%d",&n);i=n;
 if(n==1)
   printf("no");
 else
 {d=fact(n-1);
  if(d==i-1)
    printf("yes");
  else
    printf("no");}
return 0;
  }
  
int fact (int n)
  {if (n==1)
      return 1;
    
   else if(i%n==0)
    { s=s+n;
     fact(n-1);
      return (s);
      }
      
      else 
      fact(n-1);
   

  }