1007joj

 

#include<stdio.h>int main(){int n , i , j , k;while(scanf("%d", &n), n){   for(i=1;i*(i+1) < 2*n ; i++);   {   if(i*(i+1) == 2*n)   {    printf("%d is a triangular number.\n",n);    for(j = 0 ; j < i ; j ++)    {     for(k = 0 ; k <= j ;k++)      printf("*");     printf("\n");    }   }   else    printf("%d is not a triangular number.\n",n);   }}return 0;}