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417. Pacific Atlantic Water Flow.go
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417. Pacific Atlantic Water Flow.go
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package leetcode
import "math"
func pacificAtlantic(matrix [][]int) [][]int {
if len(matrix) == 0 || len(matrix[0]) == 0 {
return nil
}
row, col, res := len(matrix), len(matrix[0]), make([][]int, 0)
pacific, atlantic := make([][]bool, row), make([][]bool, row)
for i := 0; i < row; i++ {
pacific[i] = make([]bool, col)
atlantic[i] = make([]bool, col)
}
for i := 0; i < row; i++ {
dfs(matrix, i, 0, &pacific, math.MinInt32)
dfs(matrix, i, col-1, &atlantic, math.MinInt32)
}
for j := 0; j < col; j++ {
dfs(matrix, 0, j, &pacific, math.MinInt32)
dfs(matrix, row-1, j, &atlantic, math.MinInt32)
}
for i := 0; i < row; i++ {
for j := 0; j < col; j++ {
if atlantic[i][j] && pacific[i][j] {
res = append(res, []int{i, j})
}
}
}
return res
}
func dfs(matrix [][]int, row, col int, visited *[][]bool, height int) {
if row < 0 || row >= len(matrix) || col < 0 || col >= len(matrix[0]) {
return
}
if (*visited)[row][col] || matrix[row][col] < height {
return
}
(*visited)[row][col] = true
dfs(matrix, row+1, col, visited, matrix[row][col])
dfs(matrix, row-1, col, visited, matrix[row][col])
dfs(matrix, row, col+1, visited, matrix[row][col])
dfs(matrix, row, col-1, visited, matrix[row][col])
}