Submission #990375

#TimeUsernameProblemLanguageResultExecution timeMemory
990375LOLOLOPort Facility (JOI17_port_facility)C++14
22 / 100
1917 ms1048576 KiB
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
 
#define           f     first
#define           s     second
#define           pb    push_back
#define           ep    emplace
#define           eb    emplace_back
#define           lb    lower_bound
#define           ub    upper_bound
#define       all(x)    x.begin(), x.end()
#define      rall(x)    x.rbegin(), x.rend()
#define   uniquev(v)    sort(all(v)), (v).resize(unique(all(v)) - (v).begin())
#define     mem(f,x)    memset(f , x , sizeof(f))
#define        sz(x)    (ll)(x).size()
#define  __lcm(a, b)    (1ll * ((a) / __gcd((a), (b))) * (b))
#define          mxx    *max_element
#define          mnn    *min_element
#define    cntbit(x)    __builtin_popcountll(x)
#define       len(x)    (int)(x.length())
 
const int N = 2e6 + 10;
int id[N], col[N], cc = 0;
vector <int> ed[N];

void dfs(int u) {
    for (auto x : ed[u]) {
        if (col[x] == -1) {
            col[x] = 1 - col[u];
            dfs(x);
        }   

        if (col[u] == col[x]) {
            cc = 1;
        }
    }
}

ll solve() {
    mem(col, -1);
    vector <pair <int, int>> seg;
    int n;
    cin >> n;

    for (int i = 1; i <= n; i++) {
        int a, b;
        cin >> a >> b;
        seg.pb({a, b});
    }

    sort(all(seg));

    set <int> save;

    for (int i = 0; i < n; i++) {
        id[seg[i].f] = id[seg[i].s] = i;
        auto it = save.lower_bound(seg[i].f);

        while (it != save.end() && *it < seg[i].s) {
            ed[i].pb(id[*it]);
            ed[id[*it]].pb(i);
            it = next(it);
        }

        save.insert(seg[i].s);
    }

    int cnt = 0;
    for (int i = 0; i < n; i++) {
        if (col[i] == -1) {
            col[i] = 0;
            dfs(i);
            cnt++;
        }
    }

    if (cc)
        return 0;

    ll ans = 1, mod = 1e9 + 7;

    for (int i = 1; i <= cnt; i++) {
        ans = (ans + ans) % mod;
    }

    return ans;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
 
    int t = 1;
    //cin >> t;
 
    while (t--) {
        cout << solve() << '\n';
    }
 
    return 0;
} 
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