Submission #156371

#	Time	Username	Problem	Language	Result	Execution time	Memory
156371		Akashi	Potemkin cycle (CEOI15_indcyc)	C++14	100 / 100	440 ms	2552 KiB

indcyc

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

int n, m;
bool ad[1005][1005];
bool viz[1005];
int f[1005], TT[1005];
vector <int> v[1005];
vector <int> sol;
queue <int> q;

void find_path(int x, int y){
    q.push(x); viz[y] = 0;
    while(!q.empty()){
        int nod = q.front();
        q.pop();
        for(auto it : v[nod])
            if(!viz[it]) viz[it] = 1, TT[it] = nod, q.push(it);
    }

    while(y != x){
        sol.push_back(y);
        y = TT[y];
    }
    sol.push_back(x);
}

bool find(int nod){
    set <int> nodes;
    q.push(nod);
    while(!q.empty()){
        int nod = q.front();
        q.pop();
        for(auto it : v[nod]){
            if(!f[it]) f[it] = 3, q.push(it);
            if(f[it] == 2) nodes.insert(it);
        }
    }

    for(auto x : nodes){
        for(auto y : nodes){
            if(!ad[x][y] && x != y){
                find_path(x, y);
                return 1;
            }
        }
    }

    return 0;
}

bool solve(int nod){
    f[nod] = 1; viz[nod] = 1;
    for(auto it : v[nod]) viz[it] = 1, f[it] = 2;

    for(int i = 1; i <= n ; ++i) if(!f[i]){
        f[i] = 3;
        if(find(i)) return 1;
    }

    return 0;
}

int main()
{
//    freopen("1.in", "r", stdin);
    scanf("%d%d", &n, &m);

    int x, y;
    for(int i = 1; i <= m ; ++i){
        scanf("%d%d", &x, &y);
        v[x].push_back(y);
        v[y].push_back(x);
        ad[x][y] = ad[y][x] = 1;
    }

    for(int i = 1; i <= n ; ++i){
        sol.push_back(i);
        memset(f, 0, sizeof(f));
        memset(viz, 0, sizeof(viz));
        if(solve(i)) break ;
        sol.pop_back();
    }

    if(sol.size() == 0) printf("no");
    else for(auto it : sol) printf("%d ", it);


    return 0;
}

Compilation message (stderr)

indcyc.cpp: In function 'int main()':
indcyc.cpp:67:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~
indcyc.cpp:71:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &x, &y);
         ~~~~~^~~~~~~~~~~~~~~~

• 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