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+// 2872. Maximum Number of K-Divisible Components
+#include "leetcode.h"
+
+/*
+ * 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] = [a_i, b_i]' indicates that there is an edge between nodes 'a_i'
+ * and 'b_i' 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 i'th 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 thatare divisible by 'k', where the value of a connected
+ * component is the sum of the values of its node. return the maximum number of
+ * components in any valid split
+ */
+
+struct vec {
+ int *arr;
+ int size;
+};
+
+void push(struct vec *a, int val) {
+ a->arr = (int *)realloc(a->arr, (a->size + 1) * sizeof(int));
+ a->arr[a->size] = val;
+ ++a->size;
+}
+
+int dfs(int node, int parent, struct vec *adj, int *vals, int k, int *matches,
+ int n) {
+ int sum = 0, neighbour = adj[node].size;
+ for (int i = 0; i < neighbour; ++i) {
+ int n_node = adj[node].arr[i];
+ if (n_node == parent)
+ continue;
+ sum += dfs(n_node, node, adj, vals, k, matches, n);
+ }
+ sum += vals[node];
+ sum %= k;
+ if (!sum)
+ ++(*matches);
+ return sum;
+}
+
+int maxKDivisibleComponents(int n, int **edges, int edgesSize,
+ int *edgesColSize, int *values, int valuesSize,
+ int k) {
+ struct vec *adj = (struct vec *)malloc(n * sizeof(struct vec));
+ for (int i = 0; i < n; ++i)
+ adj[i] = (struct vec){(int *)malloc(0 * sizeof(int)), 0};
+ for (; edgesSize; ++edges, --edgesSize) {
+ int first = (*edges)[0], second = (*edges)[1];
+ push(adj + first, second);
+ push(adj + second, first);
+ }
+ int matches = 0;
+ dfs(0, -1, adj, values, k, &matches, n);
+ return matches;
+}
+
+int main() {
+ int e1i[4][2] = {{0, 2}, {1, 2}, {1, 3}, {2, 4}}, v1[] = {1, 8, 1, 4, 4};
+ int e2i[6][2] = {{0, 1}, {0, 2}, {1, 3}, {1, 4}, {2, 5}, {2, 6}},
+ v2[] = {3, 0, 6, 1, 5, 2, 1};
+ struct two_d_arr e1, e2;
+ two_d_arr_init(&e1, 4, 2, e1i);
+ two_d_arr_init(&e2, 6, 2, e2i);
+ printf("%d\n", maxKDivisibleComponents(5, e1.arr, e1.row_size, e1.col_size,
+ v1, ARRAY_SIZE(v1), 6)); // expect: 2
+ printf("%d\n", maxKDivisibleComponents(7, e2.arr, e2.row_size, e2.col_size,
+ v2, ARRAY_SIZE(v2), 3)); // expect: 2
+ two_d_arr_free(&e1);
+ two_d_arr_free(&e2);
+}