#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAXN = 1e5 + 25;
struct bit {
int tree[MAXN] = {};
void add (int x) {
if (x < 0 || x > MAXN) return;
for (; x < MAXN; x += x & (-x)) tree[x]++;
}
int get (int x) {
if (x < 0 || x > MAXN) return 0;
int sum = 0; for (; x; x -= x & (-x)) sum += tree[x];
return sum;
}
} cur;
int n;
string s;
vector <int> occ[26];
signed main () {
ios::sync_with_stdio(0);
cin.tie(0); memset(cur.tree, 0, sizeof(cur.tree));
cin >> n >> s;
s.insert(s.begin(), '0');
for (int i = 1; i <= n; i++) occ[s[i] - 'a'].push_back(i);
for (int i = 0; i < 26; i++) reverse(occ[i].begin(), occ[i].end());
long long cnt = 0;
string g = s;
sort(g.begin() + 1, g.begin() + n + 1);
sort(g.begin() + n + 1, g.end());
bool flag = 1;
for (int i = 1; i <= n; i++) flag &= g[i] == g[i + n];
if (!flag) return 0;
for (int i = n + 1; i <= 2 * n; i++) {
int u = occ[s[i] - 'a'].back();
occ[s[i] - 'a'].pop_back();
cnt += cur.get(u); cur.add(u);
}
cout << n * (n - 1) / 2 - cnt << '\n';
}
/*aabcdffa
adaffacb
1,2,3,4,5,6,7,8
1,5,2,6,7,8,4,3*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
1116 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
1116 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
1116 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
1116 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
1116 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
1116 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
