Submission #3027361

---

Source Code Expand

#include <bits/stdc++.h>

using namespace std;

map < pair < string, string >, int > mp;

main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  for (int mask = 0; mask < (1 << n); mask++) {
    string a, b;
    for (int i = 0; i < n; i++) {
      if ((mask >> i) & 1) {
        a += s[i];
      }
    }
    for (int i = n - 1; i >= 0; i--) {
      if ((mask >> i) & 1 ^ 1) {
        b += s[i];
      }
    }
    mp[{a, b}]++;
  }
  long long ans = 0;
  for (int mask = 0; mask < (1 << n); mask++) {
    string a, b;
    for (int i = 0; i < n; i++) {
      if ((mask >> i) & 1) {
        a += s[n + i];
      }
    }
    for (int i = n - 1; i >= 0; i--) {
      if ((mask >> i) & 1 ^ 1) {
        b += s[n + i];
      }
    }
    ans += mp[{b, a}];
  }
  cout << ans;
}

Submission Info

Judge Result