Create 107-binary-tree-level-order-traversal-ii.js

Author: everthis

107-binary-tree-level-order-traversal-ii.js

@@ -0,0 +1,25 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[][]}
+ */
+const levelOrderBottom = function(root) {
+  const levels = []
+  postOrderTraversal(root)
+  return levels.reverse()
+
+  function postOrderTraversal(node, level = 0) {
+    if (node) {
+      if (!levels[level]) levels.push([])
+      postOrderTraversal(node.left, level + 1)
+      postOrderTraversal(node.right, level + 1)
+      levels[level].push(node.val)
+    }
+  }
+}