{ "data": { "question": { "questionId": "1554", "questionFrontendId": "1443", "categoryTitle": "Algorithms", "boundTopicId": 235706, "title": "Minimum Time to Collect All Apples in a Tree", "titleSlug": "minimum-time-to-collect-all-apples-in-a-tree", "content": "

Given an undirected tree consisting of n vertices numbered from 0 to n-1, which has some apples in their vertices. You spend 1 second to walk over one edge of the tree. Return the minimum time in seconds you have to spend to collect all apples in the tree, starting at vertex 0 and coming back to this vertex.

\n\n

The edges of the undirected tree are given in the array edges, where edges[i] = [ai, bi] means that exists an edge connecting the vertices ai and bi. Additionally, there is a boolean array hasApple, where hasApple[i] = true means that vertex i has an apple; otherwise, it does not have any apple.

\n\n

 

\n

Example 1:

\n\"\"\n
\nInput: n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,true,false,true,true,false]\nOutput: 8 \nExplanation: The figure above represents the given tree where red vertices have an apple. One optimal path to collect all apples is shown by the green arrows.  \n
\n\n

Example 2:

\n\"\"\n
\nInput: n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,true,false,false,true,false]\nOutput: 6\nExplanation: The figure above represents the given tree where red vertices have an apple. One optimal path to collect all apples is shown by the green arrows.  \n
\n\n

Example 3:

\n\n
\nInput: n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,false,false,false,false,false]\nOutput: 0\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": "收集树上所有苹果的最少时间", "translatedContent": "

给你一棵有 n 个节点的无向树，节点编号为 0 到 n-1 ，它们中有一些节点有苹果。通过树上的一条边，需要花费 1 秒钟。你从 节点 0 出发，请你返回最少需要多少秒，可以收集到所有苹果，并回到节点 0 。

\n\n

无向树的边由 edges 给出，其中 edges[i] = [fromi, toi] ，表示有一条边连接 from 和 toi 。除此以外，还有一个布尔数组 hasApple ，其中 hasApple[i] = true 代表节点 i 有一个苹果，否则，节点 i 没有苹果。

\n\n

 

\n\n

示例 1：

\n\n

\"\"

\n\n
输入：n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,true,false,true,true,false]\n输出：8 \n解释：上图展示了给定的树，其中红色节点表示有苹果。一个能收集到所有苹果的最优方案由绿色箭头表示。\n
\n\n

示例 2：

\n\n

\"\"

\n\n
输入：n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,true,false,false,true,false]\n输出：6\n解释：上图展示了给定的树，其中红色节点表示有苹果。一个能收集到所有苹果的最优方案由绿色箭头表示。\n
\n\n

示例 3：

\n\n
输入：n = 7, edges = [[0,1],[0,2],[1,4],[1,5],[2,3],[2,6]], hasApple = [false,false,false,false,false,false,false]\n输出：0\n
\n\n

 

\n\n

提示：

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(listof (listof exact-integer?)) 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