Submission #651725

#	Time	Username	Problem	Language	Result	Execution time	Memory
651725		Lobo	Port Facility (JOI17_port_facility)	C++17	0 / 100	1 ms	420 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 = 2e3+10;
const int mod = 1e9+7;

int n, a[maxn], b[maxn];
pair<int,int> c[maxn];
int ds[maxn], dsl[maxn], dsr[maxn], dsant[maxn];
set<int> dsbs[maxn];
set<pair<pair<int,int>,int>> st; // mp(leftmost,rightmost,index)

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

void join(int u, int v) {
    if(u == -1 || v == -1) return;
    u = find(u);
    v = find(v);
    if(u == v) return;
    st.erase(mp(mp(dsl[u],dsr[u]),ds[u]));
    st.erase(mp(mp(dsl[v],dsr[v]),ds[v]));
    if(dsbs[u].size() < dsbs[v].size()) swap(u,v);
    ds[v] = u;
    dsl[u] = min(dsl[u],dsl[v]);
    dsr[u] = max(dsr[u],dsr[v]);
    for(auto x : dsbs[v]) dsbs[u].insert(x);
    st.insert(mp(mp(dsl[u],dsr[u]),ds[u]));
    join(dsant[u],dsant[v]);
}

void solve() {
    cin >> n;

    for(int i = 1; i <= n; i++) {
        cin >> a[i] >> b[i];
        c[i] = mp(a[i],b[i]);
    }
    sort(c+1,c+1+n);

    for(int i = 1; i <= n; i++) {
        a[i] = c[i].fr;
        b[i] = c[i].sc;
        ds[i] = i;
        dsbs[i].insert(b[i]);
        dsant[i] = -1;
        dsl[i] = b[i];
        dsr[i] = b[i];
    }

    set<int> atvs; // the b's of the past ones
    for(int i = 1; i <= n; i++) {
        // cout << st.size() << endl;
        // for(auto x : st) {
        //     cout << x.fr.fr << " " << x.fr.sc << " = " << x.sc << endl;
        // }cout << endl;

        // just be sure that we have someone in (a[i],b[i])
        auto it1 = atvs.upper_bound(a[i]);
        if(it1 == atvs.end() || *it1 > b[i]) {
            st.insert(mp(mp(b[i],b[i]),i));
            atvs.insert(b[i]);
            continue;
        }

        vector<int> idscomb; // ids that I will unite
        auto it = st.upper_bound(mp(mp(b[i],0),0)); // the first interval after b
        while(it != st.begin() && prev(it)->fr.sc > a[i]) {
            it = prev(it);
            idscomb.pb(it->sc);
        }

        st.insert(mp(mp(b[i],b[i]),i));
        atvs.insert(b[i]);
        if(idscomb.size()) {
            // combine all this and put i in the dsant of this
            int pivot = idscomb[0];
            for(int i = 1; i < idscomb.size(); i++) {
                join(pivot,idscomb[i]);
            }
            join(dsant[find(pivot)],i);
            join(dsant[find(i)],find(pivot));
            dsant[i] = pivot;
            dsant[pivot] = i;
            // cout << i << " " << pivot << " " << idscomb.size() << endl;
        }
    }

    int ans = 1;
    for(int i = 1; i <= n; i++) {
        if(find(i) == find(dsant[i])) ans = 0;
    }
    for(int i = 1; i <= n; i++) {
        // cout << i << "  --- " << find(i) << endl;
    }
    for(int i = 1; i <= n; i++) {
        join(i,dsant[i]);
        // cout << i << " -> " << dsant[i] << endl;
    }

    for(int i = 1; i <= n; i++) {
        if(find(i) == i) {
            ans*= 2;
            ans%= 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();
    }

}

Compilation message (stderr)

port_facility.cpp: In function 'void solve()':
port_facility.cpp:90:30: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |             for(int i = 1; i < idscomb.size(); i++) {
      |                            ~~^~~~~~~~~~~~~~~~

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