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 C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] input = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
            int H = input[0];
            int W = input[1];

            int[,] dp = new int[H, W];
            int maxWidth = 0;

            for (int i = 0; i < H; i++)
            {
                input = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);

                for (int j = 0; j < W; j++)
                {
                    if (input[j] == 0)
                    {
                        dp[i, j] = 1;
                        maxWidth = 1;
                    }
                }
            }

            for (int i = 1; i < H; i++)
            {
                for (int j = 1; j < W; j++)
                {
                    if (dp[i, j] != 0)
                    {
                        dp[i, j] = Math.Min(dp[i - 1, j - 1], Math.Min(dp[i - 1, j], dp[i, j - 1])) + 1;
                        maxWidth = Math.Max(maxWidth, dp[i, j]);
                    }
                }
            }

            Console.WriteLine(maxWidth * maxWidth);
        }
    }
}