題目描述

從上到下按層列印二叉樹，同一層結點從左至右輸出。每一層輸出一行。

題目地址

https://www.nowcoder.com/practice/445c44d982d04483b04a54f298796288?tpId=13&tqId=11213&rp=3&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

思路

比上題簡單，直接層次遍歷

Python

# -*- coding:utf-8 -*-
class TreeNode:
    def __init__(self, x):
        self.val 
 
= x
        self.left = None
        self.right = None
node1 = TreeNode(1)
node2 = TreeNode(2)
node3 = TreeNode(3)
node4 = TreeNode(4)
node5 = TreeNode(5)
node1.left = node2
node1.right = node3
node2.left = node4
node3.right = node5
class Solution:
    def Print(self, pRoot):
        # write code here
 

        ans = []
        if not pRoot:
            return ans
        queue = []
        queue.append(pRoot)
        while queue:
            temp = []
            for i in range(len(queue)):
                r = queue.pop(0)
                temp.append(r.val)
                if r.left:
                    queue.append(r.left)
                
 
if r.right:
                    queue.append(r.right)
            ans.append(temp)
        return ans

if __name__ == '__main__':
    # [[1] [2 3] [4 5]]
    result = Solution().Print(node1)
    print(result)