// 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); }