Problem:
Largest Square

Given a matrix (H × W) which contains only 1 and 0, find the area of the largest square matrix which only contains 0s.

Input

H W
c1,1 c1,2 ... c1,W
c2,1 c2,2 ... c2,W
:
cH,1 cH,2 ... cH,W

In the first line, two integers H and W separated by a space character are given. In the following H lines, ci,j, elements of the H × W matrix, are given.

Output

Print the area (the number of 0s) of the largest square.

Constraints

1 ≤ H, W ≤ 1,400

Sample Input

4 5
0 0 1 0 0
1 0 0 0 0
0 0 0 1 0
0 0 0 1 0

Sample Output

4

Solution in Python3 (judge verdict: Accepted)

import sys,bisect
sys.setrecursionlimit(15000)
h,w = map(int,sys.stdin.readline().split())
dp = [[0]*w for _ in range(h)]
m = 0
for i in range(h):
  a = list(map(int,sys.stdin.readline().split()))
  for j in range(w):
    if a[j] == 1:
      dp[i][j] = 0
    elif i == 0 or j == 0:
      dp[i][j] = 1
      m = max(m,dp[i][j])
    else:
      dp[i][j] = min(dp[i][j-1],dp[i-1][j],dp[i-1][j-1])+1
      m = max(m,dp[i][j])
print(m*m)