python实现leetcode之144. 二叉树的前序遍历

解题思路

深度优先即可

代码

# 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 preorderTraversal(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        rtv = []
        def dfs(tree):
            if not tree: return
            rtv.append(tree.val)
            dfs(tree.left)
            dfs(tree.right)
        
        dfs(root)
        return rtv