Submission #3789915

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
const ull mod = 1e9 + 7;
#define REP(i,n) for(int i=0;i<(int)n;++i)

//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

template < typename T >
void vprint(T &v){
	REP(i, v.size()){
		cout << v[i] << " ";
	}
	cout << endl;
}

map< pair<string, string>, ll> L, R;

int main(){
	ll N;
	string S;
	cin >> N >> S;

	ll MA = 1<<N;
	REP(i, MA){
		string pre, post;
		REP(j, N){
			if(i>>j & 1){
				pre += S[j];
			}else{
				post += S[j];
			}
		}
		L[{pre, post}]++;
	}


	ll res = 0;
	REP(i, MA){
		string pre, post;
		REP(j, N){
			if(i>>j & 1){
				pre += S[2*N-1-j];
			}else{
				post += S[2*N-1-j];
			}
		}
		res += L[{pre, post}];
	}

	cout << res << endl;

    return 0;
}

Submission Info

Judge Result