Submission #723150

#	Time	Username	Problem	Language	Result	Execution time	Memory
723150		drdilyor	Boarding Passes (BOI22_passes)	C++17	25 / 100	2070 ms	676 KiB

passes

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;

ld exp_inv(ll x) {
    return x * (x-1) / 2.0l;
}

int main() {
    char a = 'A';
    string s; cin >> s;
    const int G = 7;
    int n = s.size();
    vector memo(1<<G, (ld)-1);
    auto dp = [&](auto& dp, int used)->ld{
        if (memo[used] >= 0) return memo[used];
        if (__builtin_popcount(used) == G) return 0;
        ld res = 1e18;
        for (int i = 0 ;i < G; i++) {
            ld cur = 1e18;
            if (used&1<<i) continue;
            vector has(n, 0);
            for (int j = 0; j < n; j++) {
                if (used& 1<<(s[j] - a))
                    has[j] = 1;
            }
            for (int mid = 1; mid < n; mid++) {
                ll sum = 0;
                ll t= 0, c1{}, c2{};
                for (int j = 0; j < mid; j++) {
                    if (s[j] == i + a)
                        sum += t, c1++;
                    else t += has[j];
                }
                t = 0;
                for (int j = n-1; j >= mid; j--) {
                    if (s[j] == i + a)
                        sum += t, c2++;
                    else t += has[j];
                }
                cur = min(cur, sum + (exp_inv(c1) + exp_inv(c2)) / 2);
            }
            res = min(res, cur + dp(dp, used |1<<i));
        }
        return memo[used] = res;
    };
    cout << dp(dp, 0) << '\n';
}

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