Laskettelukeskus

#include <chrono>
#include <iostream>
#include <sstream>
#include <thread>
#include <vector>

struct Node {
    std::vector<Node*> children;

    size_t ploughs_needed;

    size_t total_ploughs() const {
        size_t csum = 0;
        for (auto* nd: children) { csum += nd->total_ploughs(); }
        return std::max(csum, ploughs_needed);
    }
};

int main() {
    //    auto s = std::string(R"(5
    // 1 2
    // 1 3
    // 3 4
    // 3 5
    // 0 2 4 3 1)");
    //    std::istringstream input(s);
    auto& input = std::cin;

    size_t count;
    input >> count;
    std::vector<Node> nodes(count);

    for (size_t i = 0; i < count - 1; ++i) {
        size_t id1, id2;
        input >> id1 >> id2;
        --id1;
        --id2;
        // id1 is higher than id2, so a plough can go id1 --> id2
        nodes[id1].children.push_back(&nodes[id2]);
    }

    for (size_t i = 0; i < count; ++i) {
        size_t num;
        input >> num;
        nodes[i].ploughs_needed = num;
    }

    std::cout << nodes[0].total_ploughs() << "\n";
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 2

Verdict: ACCEPTED

Test 5

Group: 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 1, 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 1, 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED