剑指offer 把二叉树打印成多行

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把二叉树打印成多行

题目

从上到下按层打印二叉树，同一层结点从左至右输出。每一层输出一行。

方法

方法1：宽度优先遍历

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# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回二维列表[[1,2],[4,5]]
    def Print(self, pRoot):
        # write code here
        if not pRoot:
            return []
        import collections
        queue=collections.deque([(pRoot)])
        ans=[]
        while queue:
            level=[]
            for i in range(len(queue)):
                node=queue.popleft()
                if node.left:
                    queue.append(node.left)
                if node.right:
                    queue.append(node.right)
                level.append(node.val)
            ans.append(level)
        return ans
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# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回二维列表[[1,2],[4,5]]
    def Print(self, pRoot):
        # write code here
        if not pRoot:
            return []

        queue=[pRoot]
        ans=[]
        while queue:
            value=[]
            for i in range(len(queue)):
                node=queue.pop(0)
                if node.left:
                    queue.append(node.left)
                if node.right:
                    queue.append(node.right)
                value.append(node.val)
            ans.append(value)
        return  ans