Submission #2369176

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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(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=(n)-1;i>=0;i--)
#define REPS(i,n) for(int i=1;i<=(n);i++)
#define RREPS(i,n) for(int i=(n);i>0;i--)
#define mp make_pair
#define pb(a) push_back(a)
typedef long long ll;
ll fac[100001];
const ll mod = 1e9+7;
int main(){
  int N;
  cin >> N;
  vector<pair<int,int> > v;
  REP(i,N){
    int a;
    cin >> a;
    v.pb(mp(a,-1));
  }
  REP(i,N){
    int b;
    cin >> b;
    v.pb(mp(b,1));
  }
  sort(v.begin(),v.end());
  ll ans = 1;
  int cnt = 0;
  int f = 0;
  fac[0] = 1;
  REPS(i,N) fac[i] = i*fac[i-1]%mod;
  REP(i,2*N){
    cnt++;
    f += v[i].second;
    if(f == 0){
      ans = ans*fac[cnt/2]%mod;
      cnt = 0;
    }
  }
  cout << ans << endl;
  return 0;
}

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