Untitled

import java.util.*;

class Solution {
    public int deleteTreeNodes(int nodes, int[] parent, int[] value) {
        // Step 1: Build the tree (adjacency list)
        List<List<Integer>> tree = new ArrayList<>();
        for (int i = 0; i < nodes; i++) {
            tree.add(new ArrayList<>());
        }
        
        for (int i = 1; i < nodes; i++) {
            tree.get(parent[i]).add(i);
        }
        
        // Step 2: Perform DFS to compute subtree sums and count the remaining nodes
        return dfs(0, tree, value);
    }

    private Pair dfs(int node, List<List<Integer>> tree, int[] value) {
        int subtreeSum = value[node]; // Start with the node's value
        int cnt = 0;
        // Recur for all children of the current node
        for (int child : tree.get(node)) {
            Pair obj =  dfs(child, tree, value);
            subtreesum += obj.sum;
            cnt+= obj.count;                 // Add the sum of the subtree
        }
        
        
        if (subtreeSum == 0) {
            return {0,0};
        }
        
        // If the subtree sum is non-zero, keep the node and its subtree
        return {subtreesum,cnt}; // Count the current node
    }
}