Submission #44587

#	Time	Username	Problem	Language	Result	Execution time	Memory
44587		ffresh	Port Facility (JOI17_port_facility)	C++17	22 / 100	6090 ms	5112 KiB

port_facility

#include <bits/stdc++.h>

using namespace std;

#define ll long long

const int N = 1e6+15,mod = 1e9+7;


int L[N],R[N];

int par[N],enemy[N];

int find(int a){
    if(a==-1)return -1;
    if(a==par[a])return a;
    return par[a]= find(par[a]);
}
void make_enemy(int a,int b){
    a = find(a),b = find(b);
    int u = find(enemy[a]), v = find(enemy[b]);
    if(a==b || (u!=-1 && u==v)){
        printf("0\n");
        exit(0);
    }
    if(v!=-1)par[v]= a;
    if(u!=-1)par[u]= b;
    enemy[a]= b;
    enemy[b]= a;
}

int check(int a,int b){

    int x = (L[a]<R[b] && R[b]<R[a]);
    int y= (L[a]<L[b] && L[b]<R[a]);

    if( (x+y)%2==1)return 1;
    return 0;
}
int main(){

    //freopen("input.txt","r",stdin);

    int n;
    cin>>n;
    vector<pair<int,int> >v;
    for(int i=1;i<=n;++i){
        scanf("%d%d",&L[i],&R[i]);
        v.push_back(make_pair(L[i],i));
    }
    sort(v.begin(),v.end());
    for(int i=1;i<=n;++i)par[i]= i,enemy[i]= -1;

    for(int i=1;i<=n;++i)
        for(int j=i+1;j<=n;++j){
            if(check(i,j))
                make_enemy(i,j);
        }
    long long ret= 1;
    for(int i=1;i<=n;++i){
        if(find(i)==i&& find(enemy[i])<i){
            ret= (ret*2)%mod;
        }
    }
    cout<<ret<<endl;

    return 0;
}

Compilation message (stderr)

port_facility.cpp: In function 'int main()':
port_facility.cpp:48:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&L[i],&R[i]);
         ~~~~~^~~~~~~~~~~~~~~~~~~~

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