Submission #244359

#	Time	Username	Problem	Language	Result	Execution time	Memory
244359		Osama_Alkhodairy	Port Facility (JOI17_port_facility)	C++17	0 / 100	23 ms	27776 KiB

port_facility

#include <bits/stdc++.h>
using namespace std;
#define finish(x) return cout << x << endl, 0
#define ll long long
 
const int N = 1000001;
 
int n, vis[N], p[N], mod = 1e9 + 7;
vector <pair <int, int> > a;
vector <int> f, v[N];
 
int find(int x){
    if(p[x] == x) return x;
    return p[x] = find(p[x]);
}
void merge(int x, int y){
    x = find(x);
    y = find(y);
    if(x == y){
        if(vis[x] == vis[y]){
            cout << 0 << endl;
            exit(0);
        }
        return;
    }
    p[y] = x;
    if(vis[x] == -1 && vis[y] == -1){
        v[x].push_back(y);
        v[y].push_back(x);
        vis[x] = 0;
        vis[y] = 1;
        return;
    }
    if(vis[y] == -1) swap(x, y);
    if(vis[x] == -1){
        v[x].push_back(y);
        v[y].push_back(x);
        vis[x] = vis[y] ^ 1;
        return;
    }
    if(vis[x] == (vis[y] ^ 1)){
        v[x].push_back(y);
        v[y].push_back(x);
        return;
    }
    y = v[y][0];
    assert(vis[x] == vis[y]);
    v[x].push_back(y);
    v[y].push_back(x);
}
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    memset(vis, -1, sizeof vis);
    cin >> n;
    a.resize(n);
    f.resize(2 * n);
    for(int i = 0 ; i < n ; i++){
        cin >> a[i].first >> a[i].second;
        a[i].first--; a[i].second--;
        f[a[i].first] = f[a[i].second] = i;
        p[i] = i;
    }
    vector <int> o, del(n);
    for(int i = 0 ; i < 2 * n ; i++){
        while(o.size() && del[o.back()]){
            o.pop_back();
        }
        if(a[f[i]].first == i){
            o.push_back(f[i]);
        }
        else{
            del[f[i]] = 1;
            int j = (int)o.size() - 1;
            while(o[j] != f[i]){
                if(del[o[j]] == 0){
                    merge(f[i], o[j]);
                }
                j--;
            }
        }
    }
    int ans = 1;
    for(int i = 0 ; i < n ; i++){
        if(find(i) == i){
            ans *= 2;
            if(ans >= mod) ans -= mod;
        }
    }
    cout << ans << endl;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 12
• Subtask 3: 0 / 56
• Subtask 4: 0 / 22