Create 417-pacific-atlantic-water-flow.js

Author: everthis

417-pacific-atlantic-water-flow.js

@@ -0,0 +1,37 @@
+/**
+ * @param {number[][]} matrix
+ * @return {number[][]}
+ */
+const pacificAtlantic = function(matrix) {
+  const res = []
+  if (!matrix || matrix.length === 0 || matrix[0].length === 0) return res
+  const rows = matrix.length
+  const cols = matrix[0].length
+  const dirs = [[-1, 0], [1, 0], [0, 1], [0, -1]]
+  const pacific = Array.from({ length: rows }, () => new Array(cols).fill(false))
+  const atlantic = Array.from({ length: rows }, () => new Array(cols).fill(false))
+  for (let y = 0; y < rows; y++) {
+    helper(0, y, pacific, -1, matrix, cols, rows, dirs)
+    helper(cols - 1, y, atlantic, -1, matrix, cols, rows, dirs)
+  }
+  for (let x = 0; x < cols; x++) {
+    helper(x, 0, pacific, -1, matrix, cols, rows, dirs)
+    helper(x, rows - 1, atlantic, -1, matrix, cols, rows, dirs)
+  }
+
+  for (let y = 0; y < rows; y++) {
+    for (let x = 0; x < cols; x++) {
+      if (pacific[y][x] && atlantic[y][x]) {
+        res.push([y, x])
+      }
+    }
+  }
+  return res
+}
+
+function helper(x, y, visited, height, matrix, cols, rows, dirs) {
+  if (x < 0 || x >= cols || y < 0 || y >= rows || visited[y][x] || matrix[y][x] < height) return
+  visited[y][x] = true
+  for (let dir of dirs)
+    helper(x + dir[0], y + dir[1], visited, matrix[y][x], matrix, cols, rows, dirs)
+}