Submission #4307803

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Source Code Expand

#include "bits/stdc++.h"
 
typedef long long ll;
#define int ll
#define fi first
#define se second
#define SORT(a) sort(a.begin(),a.end())
#define rep(i,n) for(int i = 0;i < (n) ; i++) 
#define REP(i,n) for(int i = 0;i < (n) ; i++) 
#define MP(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define INF LLONG_MAX/2
 
using namespace std;
int MOD = 1000000007;
int kai[100010] = {0};
signed main(){
    
    int n;
    cin >> n;
    kai[0] = kai[1] = 1;
    for(int i = 2;i <= n;i++){
        kai[i] = i*kai[i-1];
        kai[i] %= MOD;
    }
    set<pair<int,int>> s;
    rep(i,n){
        int a;
        cin >> a;
        s.insert(MP(a,0));
    }
    rep(i,n){
        int a;
        cin >> a;
        s.insert(MP(a,1));
    }
    // for(auto x:s) cerr << x.fi << " " << x.se << endl;
    int p[2] = {0};
    int prev = -1;
    int cnt = 0;
    int ans = 1;
    for(auto x:s){
        if(prev == -1){
            prev = x.se;
            p[x.se]++;
            cnt++;
        }else{
            if(prev == x.se && (p[(prev+1)%2] == 0 || p[(prev+1)%2] > p[prev])){
                cerr << " ";
                p[prev]++;
            }else if(prev != x.se && p[x.se] == 0){
                p[x.se]++;
                prev = x.se;
            }else if(p[0] == p[1] && p[0] > 0){
                ans *= kai[p[0]];
                ans %= MOD;
                p[0] = 0;
                p[1] = 0;
                prev = x.se;
                p[x.se]++;
            }
            cnt++;
        }
        cerr << cnt << " " << p[0] << " " << p[1] << " " << ans << endl;
    }
    ans *= kai[p[0]];
    ans %= MOD;
    cout << ans << endl;


    return 0;   
}
// g++ -std=c++14 code1.cpp
// rm -r -f test;oj dl https://ddcc2019-final.contest.atcoder.jp/tasks/ddcc2019_final_a
// rm -r -f test;oj dl http://cf16-exhibition-final-open.contest.atcoder.jp/tasks/cf16_exhibition_final_a

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