Submission #305194

#	Time	Username	Problem	Language	Result	Execution time	Memory
305194		adrianbudau	Network (BOI15_net)	C++17	100 / 100	509 ms	52080 KiB

net

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

void dfs(int node, int father, vector< vector<int> > &edges, vector<int> &leafs) {
    if (edges[node].size() == 1)
        leafs.push_back(node);
    for (auto &x : edges[node])
        if (x != father)
            dfs(x, node, edges, leafs);
}

int main() {
    ios::sync_with_stdio(false);

    int N; cin >> N;
    vector< vector<int> > edges(N);
    for (int i = 1; i < N; ++i) {
        int x, y; cin >> x >> y;
        edges[x - 1].push_back(y - 1);
        edges[y - 1].push_back(x - 1);
    }

    vector<int> leafs;
    for (int i = 0; i < N; ++i) {
        if (edges[i].size() == 1)
            continue;
        dfs(i, -1, edges, leafs);
        if (leafs.size() % 2)
            leafs.push_back(i);
        break;
    }

    cout << leafs.size() / 2 << "\n";
    for (int i = 0; i < int(leafs.size()) / 2; ++i)
        cout << leafs[i] + 1 << " " << leafs[i + leafs.size() / 2] + 1 << "\n";
}

• Subtask 1: 18 / 18
• Subtask 2: 45 / 45
• Subtask 3: 37 / 37