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[12/9] 1026. Maximum Difference Between Node and Ancestor

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1026. Maximum Difference Between Node and Ancestor

Given the root of a binary tree, find the maximum value v for which there exist different nodes a and b where v = |a.val - b.val| and a is an ancestor of b.

A node a is an ancestor of b if either: any child of a is equal to b or any child of a is an ancestor of b.

Example 1:

Input: root = [8,3,10,1,6,null,14,null,null,4,7,13]
Output: 7
Explanation: We have various ancestor-node differences, some of which are given below :
|8 - 3| = 5
|3 - 7| = 4
|8 - 1| = 7
|10 - 13| = 3
Among all possible differences, the maximum value of 7 is obtained by |8 - 1| = 7.

Example 2:

Input: root = [1,null,2,null,0,3]
Output: 3

Constraints:

The number of nodes in the tree is in the range [2, 5000].
0 <= Node.val <= 105

Accepted

187.7K

Submissions

247.9K

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링크

https://leetcode.com/problems/maximum-difference-between-node-and-ancestor/ 669 회 연결

익명
작성일 2022.12.09 12:40

# 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 maxAncestorDiff(self, root: Optional[TreeNode], maxval = float('-inf'), minval=float('inf')) -> int:
        if not root: return 0

        maxval = max(maxval, root.val)
        minval = min(minval, root.val)

        l = self.maxAncestorDiff(root.left, maxval, minval)
        r = self.maxAncestorDiff(root.right, maxval, minval)

        return max(l,r, abs(maxval-root.val), abs(minval-root.val))