{ "data": { "question": { "questionId": "2400", "questionFrontendId": "2322", "categoryTitle": "Algorithms", "boundTopicId": 1621121, "title": "Minimum Score After Removals on a Tree", "titleSlug": "minimum-score-after-removals-on-a-tree", "content": "
There is an undirected connected tree with n
nodes labeled from 0
to n - 1
and n - 1
edges.
You are given a 0-indexed integer array nums
of length n
where nums[i]
represents the value of the ith
node. You are also given a 2D integer array edges
of length n - 1
where edges[i] = [ai, bi]
indicates that there is an edge between nodes ai
and bi
in the tree.
Remove two distinct edges of the tree to form three connected components. For a pair of removed edges, the following steps are defined:
\n\n[4,5,7]
, [1,9]
, and [3,3,3]
. The three XOR values are 4 ^ 5 ^ 7 = 6
, 1 ^ 9 = 8
, and 3 ^ 3 ^ 3 = 3
. The largest XOR value is 8
and the smallest XOR value is 3
. The score is then 8 - 3 = 5
.Return the minimum score of any possible pair of edge removals on the given tree.
\n\n\n
Example 1:
\n\n\nInput: nums = [1,5,5,4,11], edges = [[0,1],[1,2],[1,3],[3,4]]\nOutput: 9\nExplanation: The diagram above shows a way to make a pair of removals.\n- The 1st component has nodes [1,3,4] with values [5,4,11]. Its XOR value is 5 ^ 4 ^ 11 = 10.\n- The 2nd component has node [0] with value [1]. Its XOR value is 1 = 1.\n- The 3rd component has node [2] with value [5]. Its XOR value is 5 = 5.\nThe score is the difference between the largest and smallest XOR value which is 10 - 1 = 9.\nIt can be shown that no other pair of removals will obtain a smaller score than 9.\n\n\n
Example 2:
\n\n\nInput: nums = [5,5,2,4,4,2], edges = [[0,1],[1,2],[5,2],[4,3],[1,3]]\nOutput: 0\nExplanation: The diagram above shows a way to make a pair of removals.\n- The 1st component has nodes [3,4] with values [4,4]. Its XOR value is 4 ^ 4 = 0.\n- The 2nd component has nodes [1,0] with values [5,5]. Its XOR value is 5 ^ 5 = 0.\n- The 3rd component has nodes [2,5] with values [2,2]. Its XOR value is 2 ^ 2 = 0.\nThe score is the difference between the largest and smallest XOR value which is 0 - 0 = 0.\nWe cannot obtain a smaller score than 0.\n\n\n
\n
Constraints:
\n\nn == nums.length
3 <= n <= 1000
1 <= nums[i] <= 108
edges.length == n - 1
edges[i].length == 2
0 <= ai, bi < n
ai != bi
edges
represents a valid tree.存在一棵无向连通树,树中有编号从 0
到 n - 1
的 n
个节点, 以及 n - 1
条边。
给你一个下标从 0 开始的整数数组 nums
,长度为 n
,其中 nums[i]
表示第 i
个节点的值。另给你一个二维整数数组 edges
,长度为 n - 1
,其中 edges[i] = [ai, bi]
表示树中存在一条位于节点 ai
和 bi
之间的边。
删除树中两条 不同 的边以形成三个连通组件。对于一种删除边方案,定义如下步骤以计算其分数:
\n\n[4,5,7]
、[1,9]
和 [3,3,3]
。三个异或值分别是 4 ^ 5 ^ 7 = 6
、1 ^ 9 = 8
和 3 ^ 3 ^ 3 = 3
。最大异或值是 8
,最小异或值是 3
,分数是 8 - 3 = 5
。返回在给定树上执行任意删除边方案可能的 最小 分数。
\n\n\n\n
示例 1:
\n\n输入:nums = [1,5,5,4,11], edges = [[0,1],[1,2],[1,3],[3,4]]\n输出:9\n解释:上图展示了一种删除边方案。\n- 第 1 个组件的节点是 [1,3,4] ,值是 [5,4,11] 。异或值是 5 ^ 4 ^ 11 = 10 。\n- 第 2 个组件的节点是 [0] ,值是 [1] 。异或值是 1 = 1 。\n- 第 3 个组件的节点是 [2] ,值是 [5] 。异或值是 5 = 5 。\n分数是最大异或值和最小异或值的差值,10 - 1 = 9 。\n可以证明不存在分数比 9 小的删除边方案。\n\n\n
示例 2:
\n\n输入:nums = [5,5,2,4,4,2], edges = [[0,1],[1,2],[5,2],[4,3],[1,3]]\n输出:0\n解释:上图展示了一种删除边方案。\n- 第 1 个组件的节点是 [3,4] ,值是 [4,4] 。异或值是 4 ^ 4 = 0 。\n- 第 2 个组件的节点是 [1,0] ,值是 [5,5] 。异或值是 5 ^ 5 = 0 。\n- 第 3 个组件的节点是 [2,5] ,值是 [2,2] 。异或值是 2 ^ 2 = 0 。\n分数是最大异或值和最小异或值的差值,0 - 0 = 0 。\n无法获得比 0 更小的分数 0 。\n\n\n
\n\n
提示:
\n\nn == nums.length
3 <= n <= 1000
1 <= nums[i] <= 108
edges.length == n - 1
edges[i].length == 2
0 <= ai, bi < n
ai != bi
edges
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