Submission #127178

#	Time	Username	Problem	Language	Result	Execution time	Memory
127178		Utaha	Port Facility (JOI17_port_facility)	C++14	100 / 100	1271 ms	139856 KiB

port_facility

/*input
5
1 7
4 9
2 5
6 8
3 10
*/
#include <bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pdd;
#define IOS ios_base::sync_with_stdio(0); cin.tie(0)
#define ALL(a) a.begin(),a.end()
#define SZ(a) ((int)a.size())
#define F first
#define S second
#define REP(i,n) for(int i=0;i<((int)n);i++)
#define pb emplace_back
#define MP(a,b) make_pair(a,b)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#define GET_POS(c,x) (lower_bound(c.begin(),c.end(),x)-c.begin())
template<typename T1,typename T2>
ostream& operator<<(ostream& out,pair<T1,T2> P){
    out<<'('<<P.F<<','<<P.S<<')';
    return out;
}

//}}}
const ll maxn=1000005;
const ll maxlg=__lg(maxn)+2;
const ll INF64=8000000000000000000LL;
const int INF=0x3f3f3f3f;
const ll MOD=ll(1e9+7);
const ld PI=acos(-1);
const ld eps=1e-9;
//const ll p=880301;
//const ll P=31;

ll mypow(ll a,ll b){
    ll res=1LL;
    while(b){
        if(b&1) res=res*a%MOD;
        a=a*a%MOD;
        
        b>>=1;
    }
    return res;
}

int dsu[maxn];
int sz[maxn];
int mxout[maxn];
int a[maxn],b[maxn];

int find(int u){
    if(dsu[u]==u) return u;
    return dsu[u]=find(dsu[u]);
}

vector<int> edge[maxn];
void mrg(int u,int v){
    int _u=u,_v=v;
    u=find(u);
    v=find(v);
    if(u==v) return;
    if(sz[u]<sz[v]) swap(u,v);
    dsu[v]=u;
    sz[u]+=sz[v];

    if(b[mxout[u]]<b[mxout[v]]) mxout[u]=mxout[v];
    edge[_u].pb(_v);
    edge[_v].pb(_u);
    // cout<<"mrg: "<<_u<<' '<<_v<<'\n';
}
vector<int> v;
pii tg[maxn*2];
bool type[maxn];
bool vis[maxn];

void dfs(int u){
    vis[u]=1;
    for(int v:edge[u]) if(!vis[v]){
        type[v]=!type[u];
        dfs(v);
    }
}
vector<int> A,B;
int main(){
    // freopen("in.txt","r",stdin);
    // freopen("out.txt","w",stdout);
    IOS;
    int n;
    cin>>n;
    REP(i,n) cin>>a[i]>>b[i];
    REP(i,n) a[i]--,b[i]--;
    REP(i,n) dsu[i]=i,sz[i]=1,mxout[i]=i;

    REP(i,n) tg[a[i]]=MP(i,1);
    REP(i,n) tg[b[i]]=MP(i,-1);

    int cnt=0;
    REP(i,n+n){
        if(tg[i].S==1){
            v.pb(tg[i].F);
        }
        else{
            while(find(v.back())!=find(tg[i].F)){
                mrg(tg[i].F,mxout[find(v.back())]);
                v.pop_back();
            }
            if(i==b[mxout[find(tg[i].F)]]){
                v.pop_back();
                cnt++;
            }
        }
        // for(int i:v) cout<<i<<' ';
        // cout<<'\n';
        // cout<<"dsu: \n";
        // REP(i,n) cout<<find(i)<<' '<<mxout[find(i)]<<'\n';
    }

    REP(i,n) if(!vis[i]) dfs(i);
    // REP(i,n) cout<<type[i]<<'\n';
    REP(i,n+n){
        if(tg[i].S==1){
            if(type[tg[i].F]){
                B.pb(tg[i].F);
            }
            else A.pb(tg[i].F);
        }
        else{
            if(type[tg[i].F]){
                if(B.back()!=tg[i].F){
                    cout<<"0\n";
                    return 0;
                }
                B.pop_back();
            }
            else{
                if(A.back()!=tg[i].F){
                    cout<<"0\n";
                    return 0;
                }
                A.pop_back();
            }
        }
    }

    cout<<mypow(2,cnt)<<'\n';
    return 0;
}

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