TRIANGULAR NUMBERS

Description:

"A triangular number is the number of dots in an equilateral triangle uniformly filled with dots. For example, three dots can be arranged in a triangle; thus three is a triangular number. The n-th triangular number is the number of dots in a triangle with n dots on a side. . You can learn more about these numbers from Wikipedia (http://en.wikipedia.org/wiki/Triangular_number). Your task is to find out if a given integer is a triangular number. Input The first line contains the single number n (1

Program :

  • #include <stdio.h>
    int triangle(int num)
    {
      if (num<0)
        return 0;
      int n,sum;
      for(n=1;sum<num;n++)
      {
        sum=sum+n;
        if(sum==num)
        return 1;
      }
      return 0;
    }
    int main()
    {
      int n;
      scanf("%d",&n);
      if(triangle(n))
        printf("YES");
      else
        printf("NO");
      return 0;
    }