221-maximal-square.go

package main

func maximalSquare(matrix [][]byte) int {
	m, n := len(matrix), len(matrix[0])
	dp := make([][]int, m)
	for i := 0; i < m; i++ {
		dp[i] = make([]int, n)
	}

	res := 0
	for i := 0; i < m; i++ {
		if matrix[i][0] == '1' {
			dp[i][0] = 1
			res = 1
		}
	}

	for j := 0; j < n; j++ {
		if matrix[0][j] == '1' {
			dp[0][j] = 1
			res = 1
		}
	}

	for i := 1; i < m; i++ {
		for j := 1; j < n; j++ {
			if matrix[i][j] == '1' {
				dp[i][j] = min(dp[i-1][j], min(dp[i-1][j-1], dp[i][j-1])) + 1
				if dp[i][j] > res {
					res = dp[i][j]
				}
			} else {
				dp[i][j] = 0
			}
		}
	}
	return res * res
}