제출 #1080873

#제출 시각아이디문제언어결과실행 시간메모리
1080873TymondBoarding Passes (BOI22_passes)C++17
60 / 100
2069 ms1652 KiB
#include <bits/stdc++.h> using namespace std; using ll = long long; using ld = long double; #define fi first #define se second #define vi vector<int> #define vll vector<long long> #define pii pair<int, int> #define pll pair<long long, long long> #define pb push_back #define mp make_pair #define eb emplace_back #define all(x) (x).begin(), (x).end() #define sz(x) (int)(x).size() mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); mt19937_64 rng64(chrono::steady_clock::now().time_since_epoch().count()); inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);} inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);} #ifdef DEBUG auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";} auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";} #define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X) #else #define debug(...){} #endif struct custom_hash { static uint64_t splitmix64(uint64_t x) { x += 0x9e3779b97f4a7c15; x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9; x = (x ^ (x >> 27)) * 0x94d049bb133111eb; return x ^ (x >> 31); } size_t operator()(uint64_t x) const { static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count(); return splitmix64(x + FIXED_RANDOM); } }; const int MAXN = (1 << 15) + 7; const int MAXM = 1e5 + 7; int pref[MAXM]; ld dp[MAXN]; bool in[MAXN]; int n; string s; vi pos[20]; map<char, int> col; int g; void bfs(){ queue<int> q; q.push(0); in[0] = 1; while(sz(q)){ int a = q.front(); q.pop(); for(int j = 0; j < g; j++){ if((a & (1 << j)) != 0){ continue; } for(int i = 1; i <= n; i++){ pref[i] = pref[i - 1]; if((1 << col[s[i - 1]]) & a){ pref[i]++; } } int m = sz(pos[j]); ld add = (ld)m * (m - 1) / 4; ld sumaP = 0; for(int i = 0; i < m; i++){ sumaP += (pref[n] - pref[pos[j][i]]); } add += sumaP; ld sumaL = 0; for(int i = 0; i < m; i++){ sumaP -= (pref[n] - pref[pos[j][i]]); sumaL += pref[pos[j][i]]; ld akt = (ld)i * (i + 1) / 4 + (ld)(m - i - 1) * (m - i - 2) / 4; add = min(add, akt + sumaP + sumaL); } if(!in[a + (1 << j)]){ dp[a + (1 << j)] = dp[a] + add; in[a + (1 << j)] = 1; q.push(a + (1 << j)); }else{ dp[a + (1 << j)] = min(dp[a + (1 << j)], dp[a] + add); } } } } int main(){ ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); cin >> s; n = sz(s); set<char> xd; for(auto ele : s){ xd.insert(ele); } g = sz(xd); vector<char> vec; for(auto ele : xd){ vec.pb(ele); } for(int i = 0; i < g; i++){ col[vec[i]] = i; } for(int i = 0; i < n; i++){ pos[col[s[i]]].pb(i); } if(g == 1){ ld ans = (ld)(n / 2) * (n / 2 - 1) / 4 + (ld)(n - n / 2) * (n - n / 2 - 1) / 4; cout << fixed << setprecision(5) << ans << '\n'; return 0; } bfs(); cout << fixed << setprecision(9) << dp[(1 << g) - 1] << '\n'; return 0; }
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