122 lines
2.3 KiB
C++
122 lines
2.3 KiB
C++
#include <bits/stdc++.h> // {{{
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// https://codeforces.com/blog/entry/96344
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#pragma GCC optimize("O2,unroll-loops")
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#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
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using namespace std;
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using i32 = int32_t;
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using u32 = uint32_t;
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using i64 = int64_t;
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using u64 = uint64_t;
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using d64 = double;
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using d128 = long double;
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template <typename T>
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using vec = std::vector<T>;
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template <typename T, size_t N>
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using arr = std::array<T, N>;
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template <typename T1, typename T2>
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using pai = std::pair<T1, T2>;
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template <typename T>
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constexpr T MIN = std::numeric_limits<T>::min();
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template <typename T>
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constexpr T MAX = std::numeric_limits<T>::max();
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template <typename T>
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[[nodiscard]] static T sc(auto&& x) {
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return static_cast<T>(x);
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}
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template <typename T>
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[[nodiscard]] static T sz(auto&& x) {
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return static_cast<T>(x.size());
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}
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static void NO() {
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std::cout << "NO\n";
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}
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static void YES() {
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std::cout << "YES\n";
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}
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#define all(x) (x).begin(), (x).end()
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#define rall(x) (x).rbegin(), (x).rend()
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#ifdef LOCAL
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#define db(...) std::print(__VA_ARGS__)
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#define dbln(...) std::println(__VA_ARGS__)
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#else
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#define db(...)
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#define dbln(...)
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#endif
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// }}}
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#include <bits/stdc++.h>
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using namespace std;
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void solve() {
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u32 n;
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cin >> n;
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string s;
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cin >> s;
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int ans = s.size();
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if (n & 1) {
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vector<int> pref[2] = {vector<int>(26), vector<int>(26)};
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vector<int> suf[2] = {vector<int>(26), vector<int>(26)};
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for (int i = n - 1; i >= 0; i--) {
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suf[i % 2][s[i] - 'a']++;
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}
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for (int i = 0; i < n; i++) {
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suf[i % 2][s[i] - 'a']--;
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int odd = n;
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for (int k = 0; k < 2; k++) {
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int best = 0;
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for (int j = 0; j < 26; j++) {
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best = max(best, suf[1 - k][j] + pref[k][j]);
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}
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odd -= best;
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}
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ans = min(ans, odd);
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pref[i % 2][s[i] - 'a']++;
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}
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} else {
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vector<int> v[2] = {vector<int>(26), vector<int>(26)};
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for (int i = 0; i < n; i++) {
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v[i % 2][s[i] - 'a']++;
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}
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for (int i = 0; i < 2; i++) {
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int best = 0;
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for (int j = 0; j < 26; j++) {
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best = max(best, v[i][j]);
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}
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ans -= best;
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}
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}
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cout << ans << '\n';
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}
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int main() { // {{{
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cin.tie(nullptr)->sync_with_stdio(false);
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cin.exceptions(cin.failbit);
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int tc = 1;
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cin >> tc;
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for (int t = 0; t < tc; ++t) {
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solve();
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}
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return 0;
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}
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// }}}
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