Submission #430714

#	Time	Username	Problem	Language	Result	Execution time	Memory
430714		cpp219	Port Facility (JOI17_port_facility)	C++14	100 / 100	1712 ms	108816 KiB

port_facility

#pragma GCC optimization "O2"
#pragma GCC optimization "unroll-loop"
#pragma GCC target ("avx2")

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define fs first
#define sc second
using namespace std;
const ll N = 2e6 + 9;
const ll inf = 2e9 + 7;
const ll mod = 1e9 + 7;
typedef pair<ll,ll> LL;
LL a[N];
ll n,lab[N];
set<LL> s;

ll Find(ll u){
    if (lab[u] < 0) return u;
    return lab[u] = Find(lab[u]);
}

void Union(ll p,ll q){
    ll r = Find(p),s = Find(q);
    if (r == s) return;
    if (lab[r] > lab[s]) swap(r,s);
    lab[r] += lab[s]; lab[s] = r;
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    #define task "tst"
    if (fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        //freopen(task".out", "w", stdout);
    }
    cin>>n; memset(lab,-1,sizeof(lab));
    for (ll i = 1;i <= n;i++) cin>>a[i].fs>>a[i].sc;
    sort(a + 1,a + n + 1);
    for (ll i = 1;i <= n;i++){
        auto st = s.lower_bound({a[i].fs,0}),en = s.upper_bound({a[i].sc,inf});
        if (en != s.begin()){
            for (;st != en;st++){
                Union(i,st->sc + n); Union(i + n,st->sc);
                if (Find(st->sc) == Find(prev(en)->sc)) break;
            }
        }
        s.insert({a[i].sc,i});
    }
    for (ll i = 1;i <= n;i++) if (Find(i) == Find(i + n)) return cout<<0,0;
    ll ans = 1;
    for (ll i = 1;i <= n;i++) if (Find(i) == i) ans = (ans*2)%mod;
    cout<<ans;
}

Compilation message (stderr)

port_facility.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization "O2"
      | 
port_facility.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
port_facility.cpp: In function 'int main()':
port_facility.cpp:36:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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