#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define time(code) {auto _s = chrono::high_resolution_clock::now(); code;cerr << (chrono::high_resolution_clock::now() - _s).count() / 1e9 << '\n';}
inline ll exp_inv(ll x) {
return x * (x-1);
}
int main() {
cin.tie(0)->sync_with_stdio(0);
char a = 'A';
string s; cin >> s;
const int G = 15, N = 1e5;
int n = s.size();
if (n == 1) {
cout << "0\n";
return 0;
}
ll suml[G][G][N];
ll sumr[G][G][N];
ll cr[G][N];
ll cl[G][N];
int cnt[G]{};
vector ix(G, vector<int>());
time(({
for (int c1 = 0; c1 < G; c1++) {
for (int c2 = 0; c2 < G; c2++) {
ll res = 0, cur = 0;
for (int i = 0; i < n; i++) {
if (s[i] == c1+a)
res += cur;
else if (s[i] == c2+a)
cur++;
suml[c1][c2][i] = res;
}
}
}
for (int c1 = 0; c1 < G; c1++) {
for (int c2 = 0; c2 < G; c2++) {
ll res = 0, cur = 0;
for (int i = n-1; i >= 0; i --) {
if (s[i] == c1+a)
res += cur;
else if (s[i] == c2+a)
cur++;
sumr[c1][c2][i] = res;
}
}
}
for (int j = 0; j < G; j++) {
int c = 0;
for (int i = 0; i < n;i ++) {
if (s[i] == j+a)
c++;
cl[j][i] = c;
}
}
for (int j = 0; j < G; j++) {
int c = 0;
for (int i = n-1; i >= 0; i--) {
if (s[i] == j+a)
c++;
cr[j][i] = c;
}
}
for (int i = 0; i < n; i++)
cnt[s[i] - a]++;
for (int i = 0; i < G; i++)
ix[i].reserve(cnt[i]);
for (int i = 0; i < n ;i++)
ix[s[i] - a].push_back(i);
}));
ll memo[1<<G];
memo[(1<<G)-1] = 0;
for (int used = (1<<G)-1-1; used >= 0; used--) {
ll& res = memo[used];
res = 1e18;
for (int i = 0 ;i < G; i++) {
if (used&1<<i) continue;
auto f = [&](int i, int j) {
ll sum = 0;
for (int c2 = 0; c2 < G; c2++)
if (j) sum += (used>>c2&1) * suml[i][c2][j-1];
for (int c2 = 0; c2 < G; c2++)
if (j<n) sum += (used>>c2&1) * sumr[i][c2][j];
return sum * 4 + (j < n ? exp_inv(cr[i][j]) : 0) + (j ? exp_inv(cl[i][j-1]) : 0);
};
int l = -1, r = (int)ix[i].size()-2;
while (l < r-1) {
int m = (l+r) / 2;
ll a = f(i, ix[i][m]), b = f(i, ix[i][m+1]);
else if (a < b) r = m;
else l = m;
}
ll cur = min(f(i, 0), f(i, n));;
for (int j = max(l-1, 0); j < min((int)ix[i].size(), 2 + max(0, r)); j++) {
cur = min(cur, f(i, ix[i][j]));
}
res = min(res, cur + memo[used|1<<i]);
}
};
ll ans;
ans = memo[0];
cout << ans / 4;
if (ans%4 == 1) cout << ".25";
if (ans%4 == 2) cout << ".5";
if (ans%4== 3) cout << ".75";
cout << endl;
}
Compilation message
passes.cpp: In function 'int main()':
passes.cpp:102:17: error: 'else' without a previous 'if'
102 | else if (a < b) r = m;
| ^~~~
