Submission #3226313

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define i_7 (ll)(1E9+7)
#define i_5 (ll)(1E9+5)
ll mod(ll a){
    ll c=a%i_7;
    if(c>=0)return c;
    else return c+i_7;
}
typedef pair<int,int> i_i;
typedef pair<ll,ll> l_l;
ll inf=(ll)1E12;//10^12
#define rep(i,l,r) for(ll i=l;i<=r;i++)
#define pb push_back
ll max(ll a,ll b){if(a<b)return b;else return a;}
ll min(ll a,ll b){if(a>b)return b;else return a;}
////////////////////////////////////////
#define N 200004

ll kai[N];
ll kai2[N];
ll po(ll i,ll p){
    if(p==0)return 1;
    else if(p==1)return mod(i);
    else if(p%2==0)return mod(po(mod(mod(i)*mod(i)),p/2));
    else  return mod(mod(i)*mod(po(i,p-1)));
}
void calc(){
    kai[0]=1;
    kai2[0]=1;
    for(int i=1;i<N;i++){
        kai[i]=mod(kai[i-1]*i);
        kai2[i]=mod(po(kai[i],i_5));
    }
}
ll comb(ll n,ll k){
    if(n==0){
        if(k==0)return 1;
        else return 0;
    }
    else if(n<k)return 0;
    else return mod(mod(mod(kai[n])*mod(kai2[n-k]))*mod(kai2[k]));
}


int main(){
    ios::sync_with_stdio(false);cin.tie(0);
    
    calc();
    ll n;cin>>n;
    l_l a[2*n];
    rep(i,0,n-1){
        ll b;cin>>b;a[i]=i_i(b,1);
    }
    rep(i,0,n-1){
        ll b;cin>>b;a[i+n]=i_i(b,2);
    }
    sort(a,a+2*n);
    ll ans=1;
    ll c=0;
    ll d=0;
    rep(i,0,2*n-1){
        a[i].second==1?c++:c--;
        d++;
        if(c==0){
            d/=2;
            ans=mod(ans*kai[d]);
            d=0;
        }
    }
    cout<<mod(ans)<<endl;
    
    
    return 0;
}

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