Submission #556747

#	Time	Username	Problem	Language	Result	Execution time	Memory
556747		timreizin	Teleporters (IOI08_teleporters)	C++17	100 / 100	995 ms	54408 KiB

teleporters

#include <iostream>
#include <vector>
#include <algorithm>
#include <deque>
#include <set>
#include <string>
#include <numeric>
#include <cmath>
#include <cassert>
#include <array>
#include <numeric>

using namespace std;

using ll = long long;

int dfs2(int v, vector<int> &adj, vector<bool> &used)
{
    used[v] = true;
    if (adj[v] == -1 || used[adj[v]]) return 1;
    return dfs2(adj[v], adj, used) + 1;
}

int main()
{
    cin.tie(0)->sync_with_stdio(0);
    int n, m;
    cin >> n >> m;
    vector<pair<int, int>> we(n);
    vector<pair<int, int>> closest;
    for (int i = 0; i < n; ++i)
    {
        cin >> we[i].first >> we[i].second;
        closest.push_back({we[i].first, i * 2});
        closest.push_back({we[i].second, i * 2 + 1});
    }
    sort(closest.begin(), closest.end());
    vector<int> adj(2 * n, -1);
    for (int i = 0; i < n; ++i)
    {
        auto it = upper_bound(closest.begin(), closest.end(), pair(we[i].second, (int)1e9));
        if (it != closest.end()) adj[2 * i] = it->second;
        it = upper_bound(closest.begin(), closest.end(), pair(we[i].first, (int)1e9));
        if (it != closest.end()) adj[2 * i + 1] = it->second;
    }
    int start = closest.front().second;
    vector<bool> used(2 * n);
    auto dfs = [&adj, &used](auto self, int v) -> int
    {
        used[v] = true;
        if (adj[v] == -1 || used[adj[v]]) return 1;
        return self(self, adj[v]) + 1;
    };
    int res = dfs2(start, adj, used);
    vector<int> comps;
    for (int i = 0; i < 2 * n; ++i) if (!used[i]) comps.push_back(dfs2(i, adj, used));
    sort(comps.rbegin(), comps.rend());
    for (int i = 0; i < min(m, (int)comps.size()); ++i) res += comps[i] + 2;
    m -= (int)comps.size();
    m = max(m, 0);
    res += 2 * (m - m % 2);
    res += m % 2;
    cout << res;
    return 0;
}

Compilation message (stderr)

teleporters.cpp: In function 'int main()':
teleporters.cpp:48:10: warning: variable 'dfs' set but not used [-Wunused-but-set-variable]
   48 |     auto dfs = [&adj, &used](auto self, int v) -> int
      |          ^~~

• Subtask 1: 5 / 5
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