题解 | 上三角矩阵判定
上三角矩阵判定
https://www.nowcoder.com/practice/f5a29bacfc514e5a935723857e1245e4
import sys
n = int(input())
res = "YES"
for i in range(n):
list_in = list(map(int, input().split()))
for j in range(n):
if i > 0 and j < i and list_in[j] != 0:
res = "NO"
print(res)
