Submission #1048717

#	Time	Username	Problem	Language	Result	Execution time	Memory
1048717		anton	Amusement Park (CEOI19_amusementpark)	C++17	19 / 100	3054 ms	456 KiB

amusementpark

#include<bits/stdc++.h>

using namespace std;

#define int long long
#define pii pair<int, int>
int N, M;
const int MOD = 998244353;
struct Edge{
    int sides[2];
    int dir= 0;
    Edge(){};
    Edge(int a, int b){
        sides[0] = a;
        sides[1] =b;
    }
    int dest(){
        return sides[dir];
    }
    int origin(){
        return sides[dir^1];
    }
};

vector<vector<int>> adj;
vector<Edge> edges; 


vector<int> ch(int i){
    vector<int> res;
    for(auto eid : adj[i]){
        Edge edge= edges[eid];
        if(i == edge.origin()){
            res.push_back(edge.dest());
        }
    }
    return res;
}

bool is_DAG(int mask){
    for(int i = 0; i<M; i++){
        edges[i].dir = (mask>>i)& 1;
    }
    vector<int> free;
    vector<int> in_deg(N);
    for(int i = 0; i<N; i++){
        for(auto c: ch(i)){
            in_deg[c]++;
        }
    }
    for(int i = 0; i<N; i++){
        if(in_deg[i]==0){
            free.push_back(i);
        }
    }

    while(free.size()>0){
        int i = free.back();
        free.pop_back();
        for(auto c: ch(i)){
            in_deg[c]--;
            if(in_deg[c]==0){
                free.push_back(c);
            }
        }
    }

    for(int i = 0; i<N; i++){
        if(in_deg[i]>0){
            return false;
        }
    }
    return true;
}
signed main(){
    cin.tie(NULL);
    ios_base::sync_with_stdio(false);

    cin>>N>>M;

    adj.resize(N);

    for(int i = 0; i<M; i++){
        int a, b;
        cin>>a>>b;
        a--;b--;
        edges.push_back(Edge(a, b));
        adj[a].push_back(i);
        adj[b].push_back(i);
    }

    int RES =0;
    for(int mask =1; mask < (1<<M); mask++){
        if(is_DAG(mask)){
            //cout<<bitset<3>(mask)<<endl;
            RES = (RES + __builtin_popcount(mask));
        }
    }

    cout<<RES<<endl;

}

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