题解 | 上三角矩阵判定

#include <stdio.h>

int main()
{
    int n = 0, num = 0, sum = 0;
    scanf("%d",&n);
    int i = 0, j = 0;
    for(i = 0; i < n; i++)
    {
        for(j = 0; j < n; j++)
        {
            scanf("%d",&num);
            if(j < i)
                sum += num;
        }
    }
    if(sum == 0)
        printf("YES");
    else
        printf("NO");
    return 0;
}