Submission #651956

#	Time	Username	Problem	Language	Result	Execution time	Memory
651956		Lobo	Port Facility (JOI17_port_facility)	C++17	10 / 100	1 ms	340 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], bit[maxn];
int ds[maxn], dsz[maxn];
pair<int,int> c[maxn];

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

void join(int u, int v) {
    u = find(u);
    v = find(v);
    if(u == v) return;
    if(dsz[u] < dsz[v]) swap(u,v);
    dsz[u]+= dsz[v];
    ds[v] = u;
}

void attb1(int pos, int val) {
    for(int i = pos; i <= 2*n; i+= i&-i) bit[i] = max(bit[i],val);
}
int qryb1(int pos) {
    int val = 0;
    for(int i = pos; i > 0; i-= i&-i) val = max(val,bit[i]);
    return val;
}

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;
        dsz[i] = 1;
    }

    // The graph will not be bipartite only if there exist some b1 < b2 < b3
    set<int> stb1;
    for(int i = 1; i <= n; i++) {
        stb1.insert(b[i]);
        auto it = stb1.find(b[i]);
        if(it != stb1.begin()) {
            int b1 = *prev(it);
            // adiciona o par b1,b[i]
            attb1(b[i],b1);
        }

        // If the max b1 with b2 < b[i] is > a[i], I found it
        if(qryb1(b[i]-1) > a[i]) {
            cout << 0 << endl;
            return;
        }
    }

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j < i; j++) {
            if(a[i] < b[j] && b[j] < b[i]) join(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: 0 / 12
• Subtask 3: 0 / 56
• Subtask 4: 0 / 22