Binary tree level order traversal II

Author: didi0613

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

@@ -0,0 +1,34 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[][]}
+ */
+var levelOrderBottom = function(root) {
+    if(root.left === null && root.right === null) {
+        return [[root]];
+    } else {
+        var lastLevel = [root];
+        var ret = [root];
+
+        var i=0;
+        while(lastLevel) {
+             var len = lastLevel.length;
+             var level = [];
+             for(;i<len;i++) {
+                 if(lastLevel[i].val !== '#') {
+                     level.push(lastLevel.left);
+                     level.push(lastLevel.right);
+                     i+=2;
+                 }
+             }
+             ret.unshift(level);
+             lastLevel = level;
+        }
+    }
+};