제출 #1246852

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1246852		KindaGoodGames	Amusement Park (CEOI19_amusementpark)	C++20	19 / 100	3096 ms	412 KiB

amusementpark

#include<bits/stdc++.h>

using namespace std;

#define int long long
#define pii pair<int,int>

int n,m;
int mod = 998244353;
bool validate(vector<pii>& edges){
    vector<vector<int>> adj(n);

    for(int i = 0; i < m; i++){
        int a,b;
        tie(a,b) = edges[i];
        adj[a].push_back(b);
    }

    vector<int> num(n,-1), low(n,-1);
    vector<bool> inS(n);
    stack<int> S;
    int counter = 0;
    int cnt = 0;

    auto dfs = [&](int v, auto&& dfs) -> void { 
        num[v] = low[v] = counter++;
        inS[v] = true;
        S.push(v);  
        for(auto u : adj[v]){
            if(num[u] == -1) dfs(u,dfs);
            if(inS[u]) low[v] = min(low[v], low[u]); 
        }

        if(num[v] == low[v]){
            cnt++;  
            int u;
            do{
                u = S.top(); S.pop(); inS[u] = false;
            }while(u != v);
        }
    }; 

    for(int i = 0; i < n; i++){
        if(num[i] == -1) {
            dfs(i,dfs);
        }
    }

    return cnt == n;
}
bool validate2(vector<pii>& edges){
    vector<vector<int>> adj(n);
    for(int i = 0; i < m; i++){
        int a,b;
        tie(a,b) = edges[i];
        adj[a].push_back(b);
    }

    for(int i = 0; i < n; i++){
        vector<bool> vis(n);
        stack<int> S;
        S.push(i);
        
        while(S.size()){
            int v = S.top(); S.pop();
            if(vis[v] && v == i) {
                return false;
            }
            if(vis[v]) continue;
            vis[v] = true;

            for(auto u : adj[v]){
                S.push(u);
            }
        }
    }
    return true;
}

int32_t main(){
    cin >> n >> m;
    vector<pii> edges(m); 

    for(int i = 0; i < m; i++){
        int a,b;
        cin >> a >> b;
        a--;b--;
        edges[i] = {a,b};
    }
    auto start = clock();
    
    int sum = 0;

    int p2 = 1 << m;

    for(int mask = 0; mask < p2; mask++){
        int bits = 0;
        for(int i = 0; i < m; i++){
            if(mask & (1 << i)){
                swap(edges[i].first,edges[i].second);
                bits++;
            }
        }

        if(validate(edges)){
            sum += bits;
            sum %= mod;
        } 

        if(validate(edges) != validate2(edges)){
            cerr <<"";
        }

        for(int i = 0; i < m; i++){
            if(mask & (1 << i)){
                swap(edges[i].first,edges[i].second); 
            }
        }
    }

    cout << sum << endl;

    auto end = clock();

    cerr << end - start << "ms elapsed" << endl;
}

• Subtask 1: 7 / 7
• Subtask 2: 12 / 12
• Subtask 3: 0 / 23
• Subtask 4: 0 / 21
• Subtask 5: 0 / 37