Create 778-swim-in-rising-water.js

Author: everthis

778-swim-in-rising-water.js

@@ -0,0 +1,41 @@
+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+const swimInWater = function(grid) {
+  let n = grid.length;
+  let low = grid[0][0],
+    hi = n * n - 1;
+  while (low < hi) {
+    let mid = low + Math.floor((hi - low) / 2);
+    if (valid(grid, mid)) hi = mid;
+    else low = mid + 1;
+  }
+  return low;
+};
+
+function valid(grid, waterHeight) {
+  let n = grid.length;
+  const visited = Array.from(new Array(n), el => new Array(n).fill(0));
+  const dir = [-1, 0, 1, 0, -1];
+  return dfs(grid, visited, dir, waterHeight, 0, 0, n);
+}
+function dfs(grid, visited, dir, waterHeight, row, col, n) {
+  visited[row][col] = 1;
+  for (let i = 0; i < 4; ++i) {
+    let r = row + dir[i],
+      c = col + dir[i + 1];
+    if (
+      r >= 0 &&
+      r < n &&
+      c >= 0 &&
+      c < n &&
+      visited[r][c] == 0 &&
+      grid[r][c] <= waterHeight
+    ) {
+      if (r == n - 1 && c == n - 1) return true;
+      if (dfs(grid, visited, dir, waterHeight, r, c, n)) return true;
+    }
+  }
+  return false;
+}