Submission #527453

#	Time	Username	Problem	Language	Result	Execution time	Memory
527453		joelau	Potemkin cycle (CEOI15_indcyc)	C++14	100 / 100	538 ms	94180 KiB

indcyc

#include <bits/stdc++.h>
using namespace std;

int N,M, AM[1005][1005], visited[200005], p[200005];
pair<int,int> EL[200005];
vector<int> lst[200005], ans;

void dfs (int x, int par) {
    visited[x] = 1, p[x] = par;
    for (int v: lst[x]) {
        if (visited[v] == 0) dfs(v,x);
        if (visited[v] == 1 && ans.empty()) {
            for (int i = x; i != v; i = p[i]) ans.push_back(EL[i].first);
            ans.push_back(EL[v].first);
        }
    }
    visited[x] = 2;
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    cin >> N >> M;
    memset(AM,-1,sizeof(AM));
    for (int i = 0; i < M; ++i) {
        cin >> EL[i].first >> EL[i].second;
        EL[i].first--, EL[i].second--;
        EL[i+M].first = EL[i].second, EL[i+M].second = EL[i].first;
        AM[EL[i].first][EL[i].second] = i, AM[EL[i].second][EL[i].first] = i+M;
    }
    for (int i = 0; i < M*2; ++i) for (int j = 0; j < N; ++j)
        if (j != EL[i].first && j != EL[i].second && AM[EL[i].second][j] != -1 && AM[EL[i].first][j] == -1)
            lst[i].push_back(AM[EL[i].second][j]);
    memset(visited,0,sizeof(visited));
    for (int i = 0; i < M*2 && ans.empty(); ++i) if (visited[i] == 0) dfs(i,-1);
    if (ans.empty()) cout << "no";
    else {
        int l = 0, r = ans.size()-1;
        for (int i = 0; i < ans.size(); ++i) for (int j = i+2; j < ans.size(); ++j) if (AM[ans[i]][ans[j]] != -1 && j-i < r-l) l = i, r = j;
        for (int i = l; i <= r; ++i) cout << ans[i]+1 << ' ';
    }

    return 0;
}

Compilation message (stderr)

indcyc.cpp: In function 'int main()':
indcyc.cpp:38:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |         for (int i = 0; i < ans.size(); ++i) for (int j = i+2; j < ans.size(); ++j) if (AM[ans[i]][ans[j]] != -1 && j-i < r-l) l = i, r = j;
      |                         ~~^~~~~~~~~~~~
indcyc.cpp:38:66: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |         for (int i = 0; i < ans.size(); ++i) for (int j = i+2; j < ans.size(); ++j) if (AM[ans[i]][ans[j]] != -1 && j-i < r-l) l = i, r = j;
      |                                                                ~~^~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10