Submission #1121557

#	Time	Username	Problem	Language	Result	Execution time	Memory
1121557		vjudge1	Boarding Passes (BOI22_passes)	C++17	60 / 100	2071 ms	10844 KiB

passes

#include <bits/stdc++.h>
using namespace std;
int n, g;
string s;
long double get(long double x) {
    return x * (x-1)/4;
}
int used[1111];
long double pref[100100];
long double suf[100100];
int was[1<<16][16];
long double dp[1<<16][16];
long double calc(int mask, int x) {
    if(was[mask][x]) return dp[mask][x];
    was[mask][x] = 1;
    int A = 0;
    int X = 0;
    for(int i = 0; i < n; i++) {
        pref[i+1] = pref[i];
        if(s[i] == 'A' + x) {
            pref[i+1] += A + X*0.5;
            X++;
        } else if(used[s[i] - 'A']) {
            A++;
        }
    }
    X = 0;
    A = 0;
    for(int i = n-1; i >= 0; i--) {
        suf[i] = suf[i+1];
        if(s[i] == 'A' + x) {
            suf[i] += A + X * 0.5;
            X++;
        } else if(used[s[i] - 'A']){
            A++;
        }
    }
    long double ans = 1e18;
    for(int i = 0; i < n; i++) {
        ans = min(ans, pref[i] + suf[i]);
    }
    dp[mask][x] = ans;
    return ans;
}
int main() {
    cin >> s;
    n = s.size();
    for(int i = 0; i < n; i++) {
        g = max(s[i] - 'A', g);
    }
    vector<int> p;
    for(int i = 0; i <= g; i++) {
        p.push_back(i);
    }
    //cout << g << "\n";
    long double ans = 1e18;
    do{
        for(int i = 0; i <= g; i++) {
            used[i] = 0;
        }
        long double cur = 0;
        int mask = 0;
        for(int x: p) {
            cur += calc(mask, x);
            mask |= (1<<x);
            used[x] = 1;
        }
        ans = min(ans, cur);
    }while(next_permutation(p.begin(), p.end()));
    cout << fixed << setprecision(12) << ans << "\n";
}

• Subtask 1: 5 / 5
• Subtask 2: 25 / 25
• Subtask 3: 30 / 30
• Subtask 4: 0 / 40