add 841 script.

Author: everthis

841-keys-and-rooms.js

@@ -0,0 +1,26 @@
+/**
+ * @param {number[][]} rooms
+ * @return {boolean}
+ */
+const canVisitAllRooms = function(rooms) {
+  const stack = [];
+  const seen = [];
+  for (let i = 0; i < rooms.length; i++) {
+    seen[i] = false;
+  }
+  seen[0] = true;
+  stack.push(0);
+  while (stack.length) {
+    let node = stack.pop();
+    for (let el of rooms[node]) {
+      if (!seen[el]) {
+        seen[el] = true;
+        stack.push(el);
+      }
+    }
+  }
+  for (let el of seen) {
+    if (!el) return false;
+  }
+  return true;
+};