Submission #674218

#	Time	Username	Problem	Language	Result	Execution time	Memory
674218		stanislavpolyn	Boarding Passes (BOI22_passes)	C++17	25 / 100	2 ms	1620 KiB

passes

#include <bits/stdc++.h>

#define fr(i, a, b) for (int i = (a); i <= (b); ++i)
#define rf(i, a, b) for (int i = (a); i >= (b); --i)
#define fe(x, y) for (auto& x : y)

#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define mt make_tuple

#define all(x) (x).begin(), (x).end()
#define pw(x) (1LL << (x))
#define sz(x) (int)(x).size()

using namespace std;

mt19937_64 rng(228);

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <typename T>
using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define fbo find_by_order
#define ook order_of_key

template <typename T>
bool umn(T& a, T b) { return a > b ? a = b, 1 : 0; }
template <typename T>
bool umx(T& a, T b) { return a < b ? a = b, 1 : 0; }

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <typename T>
using ve = vector<T>;

const int N = 1e5 + 5;

string s;
ve<int> v[26];

ld dp[pw(16)];
int pref[N][16];
int suff[N][16];
ve<int> p;

ld calc(int mask, int i) {
    ld sum = 0;
    int l = 0;
//    cout << "WTF " << i << "\n";
    fe (x, v[i]) {
        ld val1 = 0;
        ld val2 = 0;

        fr (i, 0, 15) {
            if (mask & pw(i)) {
                val1 += pref[x][p[i]];
                val2 += suff[x][p[i]];
            }
        }

        val1 += 0.5 * l;
        val2 += 0.5 * (sz(v[i]) - 1 - l);
//        cout << val1 << " " << val2 << "\n";

        sum += min(val1, val2);
        l++;
    }
    return sum;
}

int main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#else
    ios::sync_with_stdio(0);
    cin.tie(0);
#endif
    cin >> s;

//    fr (i, 1, 899) s.pb('A');

    fr (i, 0, sz(s) - 1) {
        v[s[i] - 'A'].pb(i);
    }

    fr (i, 0, sz(s) - 1) {
        pref[i][s[i] - 'A'] = 1;
        if (i > 0) {
            fr (j, 0, 15) {
                pref[i][j] += pref[i - 1][j];
            }
        }
    }
    rf (i, sz(s) - 1, 0) {
        suff[i][s[i] - 'A'] = 1;
        if (i + 1 < sz(s)) {
            fr (j, 0, 15) {
                suff[i][j] += suff[i + 1][j];
            }
        }
    }


    fr (i, 0, 25) {
        if (sz(v[i])) {
            p.pb(i);
        }
    }

//    fe (x, p) {
//        cout << char(x + 'A') << "\n";
//    }
//
//    cout << calc(1, 1) << "\n";
//    return 0;

    fr (mask, 0, pw(sz(p)) - 1) {
        dp[mask] = 1e18;
    }
    dp[0] = 0;

    fr (mask, 0, pw(sz(p)) - 1) {
        fr (i, 0, sz(p) - 1) {
            if (!(mask & pw(i))) {
                umn(dp[mask | pw(i)], dp[mask] + calc(mask, p[i]));
            }
        }
    }
    cout << dp[pw(sz(p)) - 1] << "\n";

//    ld res = 1e18;
//    ve<bool> act(sz(s));
//    ve<int> P(sz(s));
//    ve<int> S(sz(s));
//    ve<int> SS(sz(s));
//    ve<int> PP(sz(s));
//
//    do {
//        fill(all(act), 0);
//        fill(all(P), 0);
//        fill(all(PP), 0);
//        fill(all(S), 0);
//        fill(all(SS), 0);
//        ld ans = 0;
//
//        fe (x, p) {
//
//            fr (i, 0, sz(v[x]) - 1) {
//                PP[i] = P[v[x][i]];
//                if (i > 0) PP[i] += PP[i - 1];
//            }
//            rf (i, sz(v[x]) - 1, 0) {
//                SS[i] = S[v[x][i]];
//                if (i + 1 < sz(v[x])) SS[i] += SS[i + 1];
//            }
//
//            ld best = 1e18;
////
////            {
////                ld now = 0;
////                fr (i, 0, sz(v[x]) - 1) {
////                    ld val1 = P[v[x][i]] + i * 0.5;
////                    ld val2 = S[v[x][i]] + (sz(v[x]) - 1 - i) * 0.5;
////                    now += min(val1, val2);
////                }
////                umn(best, now);
////            }
//
//            fr (pref, 0, sz(v[x])) {
//                ld now = 0;
//                if (pref - 1 >= 0) now += PP[pref - 1];
//                if (pref < sz(v[x])) now += SS[pref];
////                fr (i, 0, pref - 1) {
////                    now += P[v[x][i]];
////                }
////                fr (i, pref, sz(v[x]) - 1) {
////                    now += S[v[x][i]];
////                }
//
//                now += ld(0.5) * pref * (pref - 1) / 2;
//                int suff = sz(v[x]) - pref;
//                now += ld(0.5) * suff * (suff - 1) / 2;
//
////                if (abs(now - 2) <= 1e-7) {
////                    cout << pref << " " << suff << "\n";
////                }
//
//                umn(best, now);
//            }
//            fe (cur, v[x]) act[cur] = 1;
//
//            fr (i, 0, sz(s) - 1) {
//                P[i] = act[i];
//                if (i > 0) P[i] += P[i - 1];
//            }
//            rf (i, sz(s) - 1, 0) {
//                S[i] = act[i];
//                if (i + 1 < sz(s)) {
//                    S[i] += S[i + 1];
//                }
//            }
////            cout << "Add " << best << " " << char(x + 'A') << "\n";
//            ans += best;
//        }
////        cout << "\n";
//        umn(res, ans);
//    } while (next_permutation(all(p)));
//
//    cout << fixed << setprecision(10) << res << "\n";

    return 0;
}

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