LeetCode in Python 872. Leaf-Similar Trees

题目描述：

Consider all the leaves of a binary tree.  From left to right order, the values of those leaves form a leaf value sequence.

For example, in the given tree above, the leaf value sequence is (6, 7, 4, 9, 8).

Two binary trees are considered leaf-similar if their leaf value sequence is the same.

Return true if and only if the two given trees with head nodes root1 and root2 are leaf-similar.

Solution:

和366. Find Leaves很像，dfs回溯分别得到叶子节点的list，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 leafSimilar(self, root1, root2):
        """
        :type root1: TreeNode
        :type root2: TreeNode
        :rtype: bool
        """
        
        def dfs(root, leaves):
            if not root:
                return
            
            if not root.left and not root.right:
                leaves.append(root.val)
            
            dfs(root.left, leaves)
            dfs(root.right, leaves)
        leftLeaves = []
        rightLeaves = []
        dfs(root1, leftLeaves)
        dfs(root2, rightLeaves)
        return leftLeaves == rightLeaves