Pseudo-Palindromic Paths in a Binary Tree.py

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def dfs(self, node, path):
        if not node:
            return
        
        if not node.left and not node.right:
            path += [node.val]
            d = {}
            for i in path.copy():
                if i in d:
                    del d[i]
                else:
                    d[i] = 1
            #print(d.items())
            self.ans += 1 if len(d) <= 1 else 0
            return
                
        self.dfs(node.left, path+[node.val])
        self.dfs(node.right, path+[node.val])
    
    def pseudoPalindromicPaths (self, root: Optional[TreeNode]) -> int:
        self.ans = 0
        self.dfs(root, [])
        return self.ans