Create 0417-pacific-atlantic-water-flow.go

Accepted submission: _https://leetcode.com/submissions/detail/870855223/_

go/0417-pacific-atlantic-water-flow.go

@@ -0,0 +1,42 @@
+func pacificAtlantic(heights [][]int) [][]int {
+    ROWS, COLS := len(heights), len(heights[0])
+    pac, atl := make(map[int]bool), make(map[int] bool)
+
+    var dfs func(int, int, map[int]bool, int)
+    dfs = func(r, c int, visit map[int]bool, prevHeight int) {
+        if (
+            visit[r*COLS + c] ||
+            r < 0 ||
+            c < 0 ||
+            r == ROWS ||
+            c == COLS ||
+            heights[r][c] < prevHeight) {
+            return;
+        }
+        visit[r*COLS + c] = true
+        dfs(r + 1, c, visit, heights[r][c])
+        dfs(r - 1, c, visit, heights[r][c])
+        dfs(r, c + 1, visit, heights[r][c])
+        dfs(r, c - 1, visit, heights[r][c])
+    }
+
+    for c := 0; c < COLS; c++ {
+        dfs(0, c, pac, heights[0][c])
+        dfs(ROWS - 1, c, atl, heights[ROWS - 1][c])
+    }
+
+    for r := 0; r < ROWS; r++ {
+        dfs(r, 0, pac, heights[r][0])
+        dfs(r, COLS - 1, atl, heights[r][COLS - 1])
+    }
+
+    res := make([][]int, 0)
+    for r := 0; r < ROWS; r++ {
+        for c := 0; c < COLS; c++ {
+            if pac[r*COLS + c] && atl[r*COLS + c] {
+                res = append(res, []int{r, c})
+            }
+        }
+    }
+    return res
+}