Submission #110589

#	Time	Username	Problem	Language	Result	Execution time	Memory
110589		someone_aa	Potemkin cycle (CEOI15_indcyc)	C++17	100 / 100	307 ms	2704 KiB

indcyc

#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define mp make_pair

using namespace std;
const int maxn = 1100;

vector<int>g[maxn];
bool edge[maxn][maxn];
bool blocked_node[maxn];
bool visited[maxn];
int parent[maxn];

int n, m;

class dsu {
public:
    int uparent[maxn], usize[maxn];
    int n;

    void init(int _n) {
        n = _n;
        for(int i=1;i<=n;i++) {
            uparent[i] = i;
            usize[i] = 1;
        }
    }
    int uroot(int x) {
        while(x != uparent[x]) {
            x = uparent[x];
        }
        return x;
    }
    void unite(int x, int y) {
        x = uroot(x);
        y = uroot(y);

        if(usize[x] > usize[y]) {
            uparent[y] = x;
            usize[x] += usize[y];
        }
        else {
            uparent[x] = y;
            usize[y] += usize[x];
        }
    }
    bool connected(int x, int y) {
        return uroot(x) == uroot(y);
    }
}D;

void dfs(int node) {
    visited[node] = true;
    if(blocked_node[node]) return;
    for(int i:g[node]) {
        if(!visited[i]) {
            //cout<<node<<" Calling "<<i<<"\n";
            dfs(i);
            D.unite(i, node);
        }
    }
}

bool find_path(int s, int i, int j) {
    memset(visited,false,sizeof(visited));

    visited[s] = true;
    visited[i] = true;

    parent[s] = 0;
    parent[i] = s;

    queue<int>q;
    q.push(i);

    while(!q.empty()) {
        int curr = q.front();
        q.pop();

        for(int i:g[curr]) {
            if(!visited[i] && (!blocked_node[i] || i == j)) {
                visited[i] = true;
                parent[i] = curr;
                q.push(i);
            }
        }
    }

    if(!visited[j]) return false;
    int x = j;
    while(x) {
        cout<<x<<" ";
        x = parent[x];
    }

    return true;
}

int main() {
    cin>>n>>m;
    int u, v;
    for(int i=0;i<m;i++) {
        cin>>u>>v;
        edge[u][v] = edge[v][u] = true;
        g[u].pb(v);
        g[v].pb(u);
    }

    bool found = false;
    for(int s=1;s<=n;s++) {
        // consider s as the start of the cycle
        // remove all edges from s, and break the graph in subgraphs

        memset(visited,false,sizeof(visited));
        memset(blocked_node,false,sizeof(blocked_node));

        visited[s] = true;
        for(auto i:g[s]) {
            blocked_node[i] = true;
        }

        D.init(n);

        for(int i=1;i<=n;i++) {
            if(!visited[i]) {
                dfs(i);
            }
        }


        for(int i:g[s]) {
            for(int j:g[s]) {
                if(i < j && !edge[i][j] && D.connected(i, j)) {
                    //cout<<s<<" call: "<<i<<" to "<<j<<"\n";
                    found = find_path(s, i, j);
                }
                if(found) break;
            }
            if(found) break;
        }
        if(found) break;
    }

    if(!found) {
        cout<<"no\n";
    }
}

• 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