//Challenge: Accepted
#include <bits/stdc++.h>
using namespace std;
#ifdef zisk
void debug(){cout << endl;}
template<class T, class ... U> void debug(T a, U ... b){cout << a << " ", debug(b...); }
template<class T> void pary(T l, T r) {
while (l != r) cout << *l << " ", l++;
cout << endl;
}
#else
#define debug(...) 0
#define pary(...) 0
#endif
#define ll long long
#define maxn 100005
#define maxc 15
#define pii pair<int, int>
#define ff first
#define ss second
#define io ios_base::sync_with_stdio(0);cin.tie(0);
const ll inf = 1LL<<60;
ll dp[1<<maxc];
int pref[maxn], suf[maxn], col[maxn];
vector<int> pos[maxc];
int main() {
io
ll n;
string s;
cin >> s;
n = s.size();
ll p = n / 2;
cout << fixed << setprecision(5) << (double)(p * (p - 1) + (n-p) * (n-p - 1)) / 4 << "\n";
return 0;
for (int i = 0;i < n;i++) {
int c = s[i] - 'A';
pos[c].push_back(i);
col[i] = c;
}
for (int i = 0;i < (1<<maxc);i++) dp[i] = inf;
dp[0] = 0;
for (int i = 0;i < (1<<maxc);i++) {
for (int j = 0;j < n;j++) {
pref[j] = suf[j] = (i >> col[j])&1;
pref[j] += j ? pref[j-1] : 0;
}
for (int j = n - 2;j >= 0;j--)suf[j] += suf[j+1];
for (int j = 0;j < maxc;j++) {
if (!((i >> j) & 1)) {
ll cur = 0, pc = 0, sc = 0;
for (int k:pos[j]) {
cur += pref[k];
pc++;
}
int to = i + (1<<j);
dp[to] = min(dp[to], dp[i] + cur*4 + pc * (pc-1));
for (int k = (int)pos[j].size() - 1;k >= 0;k--) {
sc++;
pc--;
cur += suf[pos[j][k]] - pref[pos[j][k]];
dp[to] = min(dp[to], dp[i] + cur*4 + pc * (pc-1) + sc * (sc-1));
}
}
}
}
cout << fixed << setprecision(6) << (double)dp[(1<<maxc)-1] / 4 << "\n";
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
