Submission #932333

#	Time	Username	Problem	Language	Result	Execution time	Memory
932333		alextodoran	Chorus (JOI23_chorus)	C++17	61 / 100	7102 ms	6408 KiB

chorus

/**
 _  _   __  _ _ _  _  _ _
 |a  ||t  ||o    d | |o  |
| __    _| | _ | __|  _ |
| __ |/_  | __  /__\ / _\|

**/

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;

const int N_MAX = 2000000;
const ll INF = LLONG_MAX;
const ld EPS = 1e-9;

int N, K;
int A[N_MAX + 2];

ld dp[N_MAX + 2];
int cnt[N_MAX + 2];

ll cost[N_MAX + 2];

pair <ld, int> f (int j) {
    return make_pair(dp[j] + cost[j + 1], cnt[j]);
}

ll solve (ld pen) {
    fill(cost + 1, cost + N + 1, 0);
    deque <int> rel;
    for (int i = 1; i <= N; i++) {
        for (int j = 1; j <= i; j++) {
            cost[j] += max(0, (A[i] - i + 1) - j);
        }
        pair <ld, int> mn = f(0);
        for (int j = 1; j <= i - 1; j++) {
            mn = min(mn, f(j));
        }
        tie(dp[i], cnt[i]) = mn;
        dp[i] += pen; cnt[i]++;
    }
    return (ll) round(dp[N] - pen * K);
}

int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(2);
    mt19937 rnd(time(0));

    cin >> N >> K;
//    N = 10; K = rnd() % N + 1;
    string S;
    cin >> S;
//    for (int i = 0; i < N * 2; i++) {
//        S += (i < N ? 'A' : 'B');
//    }
//    shuffle(S.begin(), S.end(), rnd);
//    cerr << N << " " << K << "\n";
//    cerr << S << "\n";
    for (int i = 0, j = 0; i < N * 2; i++) {
        if (S[i] == 'A') {
            A[++j] = i + 1;
        }
    }
    ld l = 0, r = LLONG_MAX; int iter = 150;
    while (iter--) {
        ld mid = (l + r) / 2;
        solve(mid);
        if (cnt[N] <= K) {
            r = mid;
        } else {
            l = mid + EPS;
        }
    }
    cout << solve(l) << "\n";

    return 0;
}

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 21 / 21
• Subtask 4: 0 / 26
• Subtask 5: 0 / 13