Submission #3729379

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Source Code Expand

#include<iostream>
#include<vector>
#include<algorithm>
#include<set>
#include<map>
#include<unordered_map>
#include<queue>
#include<iomanip>
#include<math.h>
#include<bitset>
#include<cassert>
#include<random>
#include<time.h>
#include<functional>
using namespace std;
using ll=long long;
using ld=long double;
using P=pair<ll,ll>;
#define MOD 1000000007LL
#define INF 1000000000LL
#define EPS 1e-10
#define FOR(i,n,m) for(ll i=n;i<(ll)m;i++)
#define REP(i,n) FOR(i,0,n)
#define DUMP(a) REP(d,a.size()){cout<<a[d];if(d!=a.size()-1)cout<<" ";else cout<<endl;}
#define ALL(v) v.begin(),v.end()
#define UNIQUE(v)  sort(ALL(v));v.erase(unique(ALL(v)),v.end());
#define pb push_back

/* --------------------------------------- */

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll n;
	cin >> n;
	vector<P> p;
	REP(i, n) {
		ll a;
		cin >> a;
		p.pb(P(a, 0));
	}
	REP(i, n) {
		ll b;
		cin >> b;
		p.pb(P(b, 1));
	}
	sort(ALL(p));
	ll ca = 0, cb = 0;
	ll ans = 1;
	REP(i, 2 * n) {
		if(p[i].second == 0) {
			if(cb == 0) ca++;
			else {
				ans *= cb; ans %= MOD;
				cb--;
			}
		} else {
			if(ca == 0) cb++;
			else {
				ans *= ca; ans %= MOD;
				ca--;
			}
		}
	}
	cout << ans << endl;
	return 0;
}

/* --------------------------------------- */

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