Submission #11356180

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Source Code Expand

#include <bits/stdc++.h>
#include <string>
#define ft first
#define sc second
#define pt(sth) cout << sth << "\n"
#define chmax(a, b) (a)=max(a, b);
#define chmin(a, b) (a)=min(a, b);
#define moC(a, s, b) (a)=((a)s(b)+MOD)%MOD
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
static const ll INF=1e18;
static const ll MAX=101010;
static const ll MOD=1e9+7;


/*
 for(i=0; i<N; i++)
   cin >> a[i];
*/


int main(void) {
  ll i, j, k;
  
  ll N;
  cin >> N;
  pll p[MAX*2];
  
  for(i=0; i<N; i++) {
    cin >> p[i].ft;
    p[i].sc=0;
  }
  for(i=N; i<N*2; i++) {
    cin >> p[i].ft;
    p[i].sc=1;
  }
  sort(p, p+N*2);
  
  if(p[0].sc==1) for(i=0; i<N*2; i++) p[i].sc=1-p[i].sc;
  
  ll fa[MAX];
  fa[0]=1;
  for(i=1; i<MAX; i++) fa[i]=fa[i-1]*i%MOD;
  
  ll ans=1;
  ll t=1;
  for(i=1; i<N*2; i++) {
    if(p[i-1].sc!=p[i].sc) moC(ans, *, fa[abs(t)]);
    
    if(p[i].sc==0) t++;
    else t--;
  }
  
  pt(ans);
  
}

Submission Info

Judge Result