Binary Tree Level Order Traversal

Author: anantkaushik

102-binary-tree-level-order-traversal.py

@@ -0,0 +1,48 @@
+"""
+Problem Link: https://leetcode.com/problems/binary-tree-level-order-traversal/
+
+Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).
+
+For example:
+Given binary tree [3,9,20,null,null,15,7],
+    3
+   / \
+  9  20
+    /  \
+   15   7
+return its level order traversal as:
+[
+  [3],
+  [9,20],
+  [15,7]
+]
+"""
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def levelOrder(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[List[int]]
+        """
+        if root is None:
+            return []
+        
+        current, res = [root], []
+        
+        while current:
+            nex, temp = [], []
+            for n in current:
+                temp.append(n.val)
+                if n.left:
+                    nex.append(n.left)
+                if n.right:
+                    nex.append(n.right)
+            current = nex
+            res.append(temp)
+        return res