Submission #4998761

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;

int main(){
	int N;
	cin >> N;
	int a[N], b[N];
	for(int i=0; i<N; i++){
		cin >> a[i];
	}
	for(int i=0; i<N; i++){
		cin >> b[i];
	}
	vector<pair<int , int>> P;
	for(int i=0; i<2*N; i++){
		if(i < N){
			P.push_back({a[i], 0});
		}else{
			P.push_back({b[i-N], 1});
		}
	}
	sort(P.begin(), P.end());
	long long ans = 1;
	int cnt = 0, c;
	for(int i=2*N-1; i>=0; i--){
		if(cnt == 0){
			c = P[i].second;
		}
		if(P[i].second != c){
			ans = (ans * cnt) % mod;
			cnt--;
		}else{
			cnt++;
		}
	}
	cout << ans << endl;
	return 0;
}

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