编辑代码

#include <stdio.h>

int main()
{
	int cnt,line,num,flag = 1;
	scanf("%d", &cnt);

	for (int i = 0; i < cnt;i++){
		scanf("%d", &line);

		for (int j = 0;j < line;j++){
            
			for(int k = 0;k < line;k++){
				scanf("%d", &num);
				if (j > k && num != 0){
					flag = 0;
				}
			}
		}
		if (flag == 0){
			printf("NO\n");
		} else{
			printf("YES\n");
		}
		flag = 1;
	}
	return 0;
}