Submission #2119148

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define pb emplace_back
typedef long long ll;
typedef pair<int,int> pint;

pint p[200001];
vector<int> v0,v1;
const int mod=1000000007;
int main(){
    int n,m,ai;
    cin>>n;
    rep(i,n){
        cin>>ai;
        p[i]={ai,0};
    }
    rep(i,n){
        cin>>ai;
        p[i+n]={ai,1};
    }
    sort(p,p+n+n);
    ll mul=1;
    rep(i,n+n){
        if(p[i].second==0){
            if(!v1.empty()){
                mul*=v1.size();v1.pop_back();
                mul%=mod;
            }
            else v0.pb(i);
        }
        else{
            if(!v0.empty()){
                mul*=v0.size();v0.pop_back();
                mul%=mod;
            }
            else v1.pb(i);
        }
    }
    cout<<mul<<endl;
    return 0;
}

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