{ "data": { "question": { "questionId": "3486", "questionFrontendId": "3249", "boundTopicId": null, "title": "Count the Number of Good Nodes", "titleSlug": "count-the-number-of-good-nodes", "content": "

There is an undirected tree with n nodes labeled from 0 to n - 1, and rooted at node 0. You are 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.

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A node is good if all the subtrees rooted at its children have the same size.

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Return the number of good nodes in the given tree.

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A subtree of treeName is a tree consisting of a node in treeName and all of its descendants.

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Example 1:

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Input: edges = [[0,1],[0,2],[1,3],[1,4],[2,5],[2,6]]

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Output: 7

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Explanation:

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All of the nodes of the given tree are good.

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Example 2:

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Input: edges = [[0,1],[1,2],[2,3],[3,4],[0,5],[1,6],[2,7],[3,8]]

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Output: 6

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Explanation:

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There are 6 good nodes in the given tree. They are colored in the image above.

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Example 3:

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Input: edges = [[0,1],[1,2],[1,3],[1,4],[0,5],[5,6],[6,7],[7,8],[0,9],[9,10],[9,12],[10,11]]

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Output: 12

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Explanation:

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All nodes except node 9 are good.

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Constraints:

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PHP 8.2.

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