[LeetCode]题解(python):103-Binary Tree Zigzag Level Order Traversal

题目来源:

  https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/



题意分析:

  Z字宽度遍历树。



题目思路:

  这题可以用比较取巧的方法。首先获得宽度遍历的结果,然后将第二层的翻转就可以了。



代码(python):

  

# 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 zigzagLevelOrder(self, root):
        """
        :type root: TreeNode
        :rtype: List[List[int]]
        """
        ans = []
        def bfs(root,level):
            if root != None:
                if len(ans) < level + 1:
                    ans.append([])
                ans[level].append(root.val)
                bfs(root.left,level + 1)
                bfs(root.right,level + 1)
        bfs(root,0)
        i = 1
        while i < len(ans):
            ans[i].reverse()
            i += 2
        return ans
                    

时间: 2024-10-05 23:50:20

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