题目：

题解：

type pair struct{ x, y int }
var dirs = []pair{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}func pacificAtlantic(heights [][]int) (ans [][]int) {m, n := len(heights), len(heights[0])pacific := make([][]bool, m)atlantic := make([][]bool, m)for i := range pacific {pacific[i] = make([]bool, n)atlantic[i] = make([]bool, n)}bfs := func(x, y int, ocean [][]bool) {if ocean[x][y] {return}ocean[x][y] = trueq := []pair{{x, y}}for len(q) > 0 {p := q[0]q = q[1:]for _, d := range dirs {if x, y := p.x+d.x, p.y+d.y; 0 <= x && x < m && 0 <= y && y < n && !ocean[x][y] && heights[x][y] >= heights[p.x][p.y] {ocean[x][y] = trueq = append(q, pair{x, y})}}}}for i := 0; i < m; i++ {bfs(i, 0, pacific)}for j := 1; j < n; j++ {bfs(0, j, pacific)}for i := 0; i < m; i++ {bfs(i, n-1, atlantic)}for j := 0; j < n-1; j++ {bfs(m-1, j, atlantic)}for i, row := range pacific {for j, ok := range row {if ok && atlantic[i][j] {ans = append(ans, []int{i, j})}}}return
}