Submission #2443568

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
ll N,a;
ll inf = 1e9+7;
ll F[100010] = {0};

int main(){
	cin >> N;
	F[0] = 1;
	for(int i=1;i<=N;i++){
		F[i] = (i*F[i-1])%inf;
	}
	vector<P> v(2*N);
	for(int i=0;i<2*N;i++){
		if(i<N){
			cin >> a;
			v[i] = P(a,1);
		}else{
			cin >> a;
			v[i] = P(a,-1);
		}
	}
	sort(v.begin(),v.end());
	ll  c = 0,ma = 0;
	ll ans = 1;
	for(int i=0;i<2*N;i++){
		c += v[i].second;
		ma = max(ma,c);
		if(c==0){
			(ans *= F[ma])%inf;
			ma = 0;
		}
	}
	cout << ans << endl;
}

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