题解 | 上三角矩阵判定
上三角矩阵判定
https://www.nowcoder.com/practice/f5a29bacfc514e5a935723857e1245e4
n=int(input())
A=[]
for i in range(n):
a=list(map(int,input().split()))
A.append(a)
c=True
for i in range(n):
for j in range(0,i):
if A[i][j]!=0:
c=False
break
if c==True:
print("YES")
else:
print("NO")
