2872-maximum-number-of-k-divisible-components.js

/**
 * 2872. Maximum Number of K-Divisible Components
 * https://leetcode.com/problems/maximum-number-of-k-divisible-components/
 * Difficulty: Hard
 *
 * 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.
 */

/**
 * @param {number} n
 * @param {number[][]} edges
 * @param {number[]} values
 * @param {number} k
 * @return {number}
 */
var maxKDivisibleComponents = function(n, edges, values, k) {
  const graph = Array.from({ length: n }, () => []);
  for (const [u, v] of edges) {
    graph[u].push(v);
    graph[v].push(u);
  }

  let result = 0;
  dfs(0, -1);
  return result;

  function dfs(node, parent) {
    let total = values[node];
    for (const neighbor of graph[node]) {
      if (neighbor !== parent) {
        total += dfs(neighbor, node);
      }
    }
    if (total % k === 0) {
      result++;
      return 0;
    }
    return total;
  }
};