{ "data": { "question": { "questionId": "2717", "questionFrontendId": "6356", "categoryTitle": "Algorithms", "boundTopicId": 2184007, "title": "Collect Coins in a Tree", "titleSlug": "collect-coins-in-a-tree", "content": "

There exists an undirected and unrooted tree with n nodes indexed from 0 to n - 1. You are given an integer n and 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. You are also given an array coins of size n where coins[i] can be either 0 or 1, where 1 indicates the presence of a coin in the vertex i.

\n\n

Initially, you choose to start at any vertex in the tree. Then, you can perform the following operations any number of times: 

\n\n\n\n

Find the minimum number of edges you need to go through to collect all the coins and go back to the initial vertex.

\n\n

Note that if you pass an edge several times, you need to count it into the answer several times.

\n\n

 

\n

Example 1:

\n\"\"\n
\nInput: coins = [1,0,0,0,0,1], edges = [[0,1],[1,2],[2,3],[3,4],[4,5]]\nOutput: 2\nExplanation: Start at vertex 2, collect the coin at vertex 0, move to vertex 3, collect the coin at vertex 5 then move back to vertex 2.\n
\n\n

Example 2:

\n\"\"\n
\nInput: coins = [0,0,0,1,1,0,0,1], edges = [[0,1],[0,2],[1,3],[1,4],[2,5],[5,6],[5,7]]\nOutput: 2\nExplanation: Start at vertex 0, collect the coins at vertices 4 and 3, move to vertex 2,  collect the coin at vertex 7, then move back to vertex 0.\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": "收集树中金币", "translatedContent": "

给你一个 n 个节点的无向无根树，节点编号从 0 到 n - 1 。给你整数 n 和一个长度为 n - 1 的二维整数数组 edges ，其中 edges[i] = [ai, bi] 表示树中节点 ai 和 bi 之间有一条边。再给你一个长度为 n 的数组 coins ，其中 coins[i] 可能为 0 也可能为 1 ，1 表示节点 i 处有一个金币。

\n\n

一开始，你需要选择树中任意一个节点出发。你可以执行下述操作任意次：

\n\n\n\n

你需要收集树中所有的金币，并且回到出发节点，请你返回最少经过的边数。

\n\n

如果你多次经过一条边，每一次经过都会给答案加一。

\n\n

 

\n\n

示例 1：

\n\n

\"\"

\n\n
输入：coins = [1,0,0,0,0,1], edges = [[0,1],[1,2],[2,3],[3,4],[4,5]]\n输出：2\n解释：从节点 2 出发，收集节点 0 处的金币，移动到节点 3 ，收集节点 5 处的金币，然后移动回节点 2 。\n
\n\n

示例 2：

\n\n

\"\"

\n\n
输入：coins = [0,0,0,1,1,0,0,1], edges = [[0,1],[0,2],[1,3],[1,4],[2,5],[5,6],[5,7]]\n输出：2\n解释：从节点 0 出发，收集节点 4 和 3 处的金币，移动到节点 2 处，收集节点 7 处的金币，移动回节点 0 。\n
\n\n

 

\n\n

提示：

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The remaining nodes in the tree are the ones that must be visited. Hence, the answer is equal to (# remaining nodes -1) * 2" ], "solution": null, "status": null, "sampleTestCase": "[1,0,0,0,0,1]\n[[0,1],[1,2],[2,3],[3,4],[4,5]]", "metaData": "{\n \"name\": \"collectTheCoins\",\n \"params\": [\n {\n \"name\": \"coins\",\n \"type\": \"integer[]\"\n },\n {\n \"type\": \"integer[][]\",\n \"name\": \"edges\"\n }\n ],\n \"return\": {\n \"type\": \"integer\"\n }\n}", "judgerAvailable": true, "judgeType": "large", "mysqlSchemas": [], "enableRunCode": true, "envInfo": "{\"cpp\":[\"C++\",\"

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