Submission #652485

#	Time	Username	Problem	Language	Result	Execution time	Memory
652485		Lobo	Port Facility (JOI17_port_facility)	C++17	22 / 100	6021 ms	136416 KiB

port_facility

#include<bits/stdc++.h>
using namespace std;
const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()

const int maxn = 1e6+10;
const int mod = 1e9+7;

int n, a[maxn], b[maxn];
int ds[maxn], dsz[maxn], dsgrp[maxn];
vector<int> dsvec[maxn];
set<int> dsgrpbs[maxn][2];

int find(int v) {
    if(v == ds[v]) return v;
    return ds[v] = find(ds[v]);
}

void createedge(int u, int v) {
    // an edge from u to v
    int u1 = u;
    int v1 = v;
    int chg = 1; // dsgrp[v] = dsgrp[u]^chg, basically 0 if from the same group and 1 if not
    u = find(u);
    v = find(v);

    if(dsgrp[u1] != dsgrp[u]) chg^= 1;
    if(dsgrp[v1] != dsgrp[v]) chg^= 1;

    if(u == v) {
        if(chg == 1) {
            // I fail, because they are equal
            cout << 0 << endl;
            exit(0);
        }
        else {
            // stop the uniting
            return;
        }
    }

    if(dsz[u] < dsz[v]) {
        swap(u,v);
        swap(u1,v1);
    }

    // Now I insert all the ones from v in u
    ds[v] = u;
    dsz[u]+= dsz[v];
    for(auto id : dsvec[v]) {
        // Insert id in u as dsgrp[id]^chg
        dsgrp[id]^= chg;
        dsgrpbs[u][dsgrp[id]].insert(b[id]);
        dsvec[u].pb(id);
    }
}

void solve() {
    cin >> n;
    vector<pair<int,int>> wtfsort;
    for(int i = 1; i <= n; i++) {
        cin >> a[i] >> b[i];
        wtfsort.pb(mp(a[i],b[i]));
    }
    sort(all(wtfsort));
    for(int i = 1; i <= n; i++) {
        a[i] = wtfsort[i-1].fr;
        b[i] = wtfsort[i-1].sc;
        ds[i] = i;
        dsz[i] = 1;
        dsvec[i].pb(i);
        dsgrp[i] = 0;
        dsgrpbs[i][0].insert(b[i]);
    }

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j < i; j++) {
            if(b[j] > a[i] && b[j] < b[i]) {
                createedge(i,j);
            }
        }
    }
    int ans = 1;
    for(int i = 1; i <= n; i++) {
        if(find(i) == i) ans = ans*2%mod;
    }
    cout << ans << endl;
}

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(0);

    // freopen("in.in", "r", stdin);
    // freopen("out.out", "w", stdout);
    int tt = 1;
    // cin >> tt;
    while(tt--) {
        solve();
    }

}

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