Submission #703586

#	Time	Username	Problem	Language	Result	Execution time	Memory
703586		sheldon	Senior Postmen (BOI14_postmen)	C++17	100 / 100	403 ms	50096 KiB

postmen

#include <bits/stdc++.h>

using namespace std;

const int nax = 5e5 + 5;

vector<pair<int, int>> edges[nax];
int deg[nax], where[nax];
bool used[nax];

void solve() {
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int u, v;
        cin >> u >> v;
        ++deg[u], ++deg[v];
        edges[u].push_back({v, i});
        edges[v].push_back({u, i});
    }
    vector<int> st = {1}, ans;
    int at = 1;
    while (!st.empty()) {
        if (deg[at]) {
            st.push_back(at);
            while (used[edges[at].back().second]) {
                edges[at].pop_back();
            }
            --deg[at];
            used[edges[at].back().second] = 1;
            at = edges[at].back().first;
            --deg[at];
        } else {
            ans.push_back(at);
            at = st.back();
            st.pop_back();
        }
    }
    vector<pair<int, int>> stt;
    for (int i = 0; i < nax; ++i) {
        where[i] = -1;
    }
    for (int i = 0; i < ans.size(); ++i) {
        stt.push_back({ans[i], i});
        if (where[ans[i]] != -1) {
            int x = where[ans[i]];
            while (stt.back().second > x) {
                where[stt.back().first] = -1;
                cout << stt.back().first << ' ';
                stt.pop_back();
            }
            where[ans[i]] = stt.back().second;
            cout << '\n';
        } else {
            where[ans[i]] = i;
        }
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    solve();
}

Compilation message (stderr)

postmen.cpp: In function 'void solve()':
postmen.cpp:43:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |     for (int i = 0; i < ans.size(); ++i) {
      |                     ~~^~~~~~~~~~~~

• Subtask 1: 38 / 38
• Subtask 2: 17 / 17
• Subtask 3: 45 / 45