Add solution and test-cases for problem 2872

Author: 0xff-dev

leetcode/2801-2900/2872.Maximum-Number-Of-K-Divisible-Components/README.md

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+# [2872.Maximum Number of K-Divisible Components][title]
+
+## Description
+There is an undirected tree with `n` nodes labeled from `0` to `n - 1`. You are given the 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 a **0-indexed** integer array `values` of length `n`, where `values[i]` is the **value** associated with the `ith` node, and an integer `k`.
+
+A **valid split** of the tree is obtained by removing any set of edges, possibly empty, from the tree such that the resulting components all have values that are divisible by `k`, where the **value of a connected component** is the sum of the values of its nodes.
+
+Return the **maximum number of components** in any valid split.
+
+
+**Example 1:**
+
+```
+Input: n = 5, edges = [[0,2],[1,2],[1,3],[2,4]], values = [1,8,1,4,4], k = 6
+Output: 2
+Explanation: We remove the edge connecting node 1 with 2. The resulting split is valid because:
+- The value of the component containing nodes 1 and 3 is values[1] + values[3] = 12.
+- The value of the component containing nodes 0, 2, and 4 is values[0] + values[2] + values[4] = 6.
+It can be shown that no other valid split has more than 2 connected components.
+```
+
+**Example 2:**
+
+```
+Input: n = 7, edges = [[0,1],[0,2],[1,3],[1,4],[2,5],[2,6]], values = [3,0,6,1,5,2,1], k = 3
+Output: 3
+Explanation: We remove the edge connecting node 0 with 2, and the edge connecting node 0 with 1. The resulting split is valid because:
+- The value of the component containing node 0 is values[0] = 3.
+- The value of the component containing nodes 2, 5, and 6 is values[2] + values[5] + values[6] = 9.
+- The value of the component containing nodes 1, 3, and 4 is values[1] + values[3] + values[4] = 6.
+It can be shown that no other valid split has more than 3 connected components.
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/maximum-number-of-k-divisible-components/
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/2801-2900/2872.Maximum-Number-Of-K-Divisible-Components/Solution.go

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+package Solution
+
+func Solution(n int, edges [][]int, values []int, k int) int {
+	for i := range values {
+		values[i] %= k
+	}
+	adj := make([][]int, n)
+	for _, e := range edges {
+		a, b := e[0], e[1]
+		adj[a] = append(adj[a], b)
+		adj[b] = append(adj[b], a)
+	}
+
+	count := 0
+	var dfs func(int, int) int
+	dfs = func(parent, cur int) int {
+		s := 0
+		for _, nei := range adj[cur] {
+			if nei == parent {
+				continue
+			}
+			s = (s + dfs(cur, nei)) % k
+		}
+		s = (s + values[cur]) % k
+		if s == 0 {
+			count++
+		}
+		return s
+	}
+	dfs(-1, 0)
+	return count
+}

leetcode/2801-2900/2872.Maximum-Number-Of-K-Divisible-Components/Solution_test.go

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+package Solution
+
+import (
+	"reflect"
+	"strconv"
+	"testing"
+)
+
+func TestSolution(t *testing.T) {
+	//	测试用例
+	cases := []struct {
+		name   string
+		n      int
+		edges  [][]int
+		values []int
+		k      int
+		expect int
+	}{
+		{"TestCase1", 5, [][]int{{0, 2}, {1, 2}, {1, 3}, {2, 4}}, []int{1, 8, 1, 4, 4}, 6, 2},
+		{"TestCase2", 7, [][]int{{0, 1}, {0, 2}, {1, 3}, {1, 4}, {2, 5}, {2, 6}}, []int{3, 0, 6, 1, 5, 2, 1}, 3, 3},
+	}
+
+	//	开始测试
+	for i, c := range cases {
+		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
+			got := Solution(c.n, c.edges, c.values, c.k)
+			if !reflect.DeepEqual(got, c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v %v %v %v",
+					c.expect, got, c.n, c.edges, c.values, c.k)
+			}
+		})
+	}
+}
+
+// 压力测试
+func BenchmarkSolution(b *testing.B) {
+}
+
+// 使用案列
+func ExampleSolution() {
+}