golang力扣leetcode 221.最大正方形

state: dp[i][j]：以i，j为右下角的正方形的最大边长
function: dp[i][j] = min(dp[i-1][j], dp[i-1][j-1], dp[i][j-1]) + 1
intialize: 
answer: 

func maximalSquare(matrix [][]byte) int {
  n, m := len(matrix), len(matrix[0])
  dp := make([][]int, n+1)
  for i := range dp {
    dp[i] = make([]int, m+1)
  }
  ans := 0
  for i := 1; i <= n; i++ {
    for j := 1; j <= m; j++ {
      cnt := matrix[i-1][j-1]
      if cnt == '1' {
        dp[i][j] = min(dp[i-1][j], dp[i-1][j-1], dp[i][j-1]) + 1
      } else {
        dp[i][j] = 0
      }
      ans = max(ans, dp[i][j])
    }
  }
  return ans * ans
}
func max(i, j int) int {
  if i > j {
    return i
  }
  return j
}
func min(i, j, k int) int {
  return min1(min1(i, j), k)
}
func min1(i, j int) int {
  if i > j {
    return j
  }
  return i
}