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 import Queue class Solution(object): def levelOrder(self, root): """ :type root: TreeNode :rtype: List[List[int]] """ rlist=[] if root==None: return rlist q=Queue.Queue() q.put(root) while q.empty()!=True: count=q.qsize() sublist=[] for i in range(count): x=q.get() sublist.append(x.val) if x.left!=None: q.put(x.left) if x.right!=None: q.put(x.right) rlist.append(sublist) return rlist
# 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 ==None: return [] rlist=[] nodelist=[root] while nodelist!=[]: sublist=[l.val for l in nodelist if l] templist=[] for i in nodelist: if i!=None: if i.left:templist.append(i.left) if i.right:templist.append(i.right) nodelist= templist rlist.append(sublist) return rlist