Submission #447257

#TimeUsernameProblemLanguageResultExecution timeMemory
447257alan8585Port Facility (JOI17_port_facility)C++14
22 / 100
6039 ms4692 KiB
#pragma GCC optimize ("Ofast","unroll-loops")
#include <bits/stdc++.h>
#define pb push_back
#define eb emplace_back
#define MP make_pair
#define F first
#define S second
#define setpre(a) cout.precision(a),cout<<fixed;
#define ALL(a) a.begin(),a.end()
#define MEM(a,b) memset(a,b,sizeof a)
#define Tie ios::sync_with_stdio(0),cin.tie(0);
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pdd;

struct datas {
    int x, y, id;
    bool operator<(const datas &a) {
        return x < a.x;
    }
};

int n;
vector<datas> ori, v, tv;
vector<int> C;

int find(int a) {
    if(C[a] != a) return C[a] = find(C[a]);
    return a;
}

void merge(int a, int b) {
    // cout << a << ' ' << b << '\n';
    a = find(a);
    b = find(b);
    if(a == b) return;
    C[a] = b;
}

// bool is_vali() {
//     sort(ALL(v));
//     stack<int> st1, st2;
//     for(datas &i : v) {
//         while(!st1.empty() && st1.top() < i.x)
//             st1.pop();
//         while(!st2.empty() && st2.top() < i.x)
//             st2.pop();
//         if(st1.empty() || st1.top() > i.y)
//             st1.push(i.y);
//         else if(st2.empty() || st2.top() > i.y)
//             st2.push(i.y);
//         else
//             return 0;
//     }
//     return 1;
// }

int main() {Tie
    cin >> n;
    v.resize(n), C.resize(n * 2);
    for(int i = 0; i < n; i++) {
        cin >> v[i].x >> v[i].y;
        v[i].id = i;
    }
    for(int i = 0; i < n * 2; i++)
        C[i] = i;
    ori = v;
    // if(!is_vali()) {
    //     cout << "0\n";
    //     return 0;
    // }
    v = ori;
    sort(ALL(v));
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < n; j++) {
            if(v[i].x < v[j].x && v[i].y < v[j].y && v[j].x < v[i].y) {
                merge(i, j + n);
                merge(i + n, j);
            }
        }
    }
    int ans = 1;
    for(int i = 0; i < n; i++)
        if(find(i) == find(i + n))
            ans = 0;
    for(int i = 0; i < n; i++)
        if(find(i) == i)
            ans = (ans << 1) % 1000000007;
    cout << ans << '\n';
}
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