golang力扣leetcode 1020.飞地的数量

package main
func numEnclaves(grid [][]int) int {
  var dirs = []struct{ x, y int }{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}
  var vis = make([][]bool, len(grid))
  for i, v := range grid {
    vis[i] = make([]bool, len(v))
  }
  var dfs func(int, int)
  dfs = func(x, y int) {
    if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) || vis[x][y] || grid[x][y] == 0 {
      return
    }
    vis[x][y] = true
    for _, v := range dirs {
      dfs(x+v.x, y+v.y)
    }
  }
  for i := range grid {
    dfs(i, 0)
    dfs(i, len(grid[0])-1)
  }
  for i := 0; i <= len(grid[0])-1; i++ {
    dfs(0, i)
    dfs(len(grid)-1, i)
  }
  ans := 0
  for i, v := range grid {
    for j := range v {
      if grid[i][j] == 1 && vis[i][j] == false {
        ans++
      }
    }
  }
  return ans
}