leetcode——687. 最长同值路径

class Solution:
    def longestUnivaluePath(self, root: TreeNode) -> int:
        self.ans=0
        def arrow_length(node):
            if not node:
                return 0
            left_length=arrow_length(node.left)
            right_length=arrow_length(node.right)
            left_arrow=right_arrow=0
            if node.left and node.left.val==node.val:
                left_arrow=left_length+1
            if node.right and node.right.val==node.val:
                right_arrow=right_length+1
            self.ans=max(self.ans,left_arrow+right_arrow)
            return max(left_arrow,right_arrow)
        arrow_length(root)
        return self.ans

执行用时 :536 ms, 在所有 python3 提交中击败了40.17%的用户

内存消耗 :17.9 MB, 在所有 python3 提交中击败了6.10%的用户

 

——2019.11.21