Submission #1131222

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Source Code Expand

#include<vector>
#include<cmath>
#include<map>
#include<cstdlib>
#include<iostream>
#include<sstream>
#include<fstream>
#include<string>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<set>
#include<stack>
#include<bitset>
#include<functional>
#include<ctime>
#include<queue>
#include<deque>
#include<complex>
#include<cassert>
using namespace std;
#define pb push_back
#define pf push_front
typedef long long lint;
typedef complex<double> P;
#define mp make_pair
#define fi first
#define se second
typedef pair<int,int> pint;
#define All(s) s.begin(),s.end()
#define rAll(s) s.rbegin(),s.rend()
#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
int x[114514];
bool sumi[114514];
int n;
/*bool cal(vector<int> a){
	memset(sumi,false,sizeof(sumi));
	rep(i,n){
		int sum=0,f=0;
		rep(j,a[i]){
			if(sumi[j]) continue;
			sum++;if(sum*2>=x[j]+2) f=1;
		}
		if(f>0) return false;
		sumi[a[i]]=true;
	}
	return true;
}*/
int main()
{
	lint out=1,mo=1000000007;
	cin>>n;
	rep(i,n) cin>>x[i];
	/*if(n>8) return 0;
	vector<int> v;rep(i,n) v.pb(i);
	while(1){
		if(cal(v)) out++;
		if(!next_permutation(All(v))) break;
	}*/
	//memset(sumi,false,sizeof(sumi));
	int sum=0,f=0;
	rep(i,n){
		sum++;
		if(sum*2>=x[i]+2){
			out*=sum;out%=mo;sum--;
		}
	}
	REP(i,1,sum+1){
		out*=i;out%=mo;
	}
	cout<<out<<endl;
}

Submission Info

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