golang力扣leetcode 542.01 矩阵

BFS 从0进队列，弹出之后计算上下左右的结果，将上下左右重新进队列进行二层操作
0 0 0 0
0 x 0 0
x x x 0
0 x 0 0
0 0 0 0
0 1 0 0
1 x 1 0
0 1 0 0
0 0 0 0
0 1 0 0
1 2 1 0
0 1 0 0

package main
func updateMatrix(mat [][]int) [][]int {
  var queue [][]int
  for i := 0; i < len(mat); i++ {
    for j := 0; j < len(mat[i]); j++ {
      if mat[i][j] == 0 {
        point := []int{i, j}
        queue = append(queue, point)
      } else {
        mat[i][j] = -1
      }
    }
  }
  dir := [][]int{{0, 1}, {0, -1}, {-1, 0}, {1, 0}}
  for len(queue) != 0 {
    //pop
    point := queue[0]
    queue = queue[1:]
    //bfs
    for _, v := range dir {
      x := point[0] + v[0]
      y := point[1] + v[1]
      //如果没有超出边界并且是-1的那些数
      if x >= 0 && x < len(mat) && y >= 0 && y < len(mat[0]) && mat[x][y] == -1 {
        mat[x][y] = mat[point[0]][point[1]] + 1
        queue = append(queue, []int{x, y})
      }
    }
  }
  return mat
}