Submission #746268

#	Time	Username	Problem	Language	Result	Execution time	Memory
746268		baluteshih	Chorus (JOI23_chorus)	C++14	16 / 100	101 ms	10156 KiB

chorus

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define X first
#define Y second
#define SZ(a) ((int)a.size())
#define ALL(v) v.begin(), v.end()
#define pb push_back

struct node {
    int first, sz;
    ll sum;
};

int lft[1000005];
list<node>::iterator arr[1000005];

int main() {
    ios::sync_with_stdio(0), cin.tie(0);
    int n, k;
    long long ans = 0;
    string s;
    cin >> n >> k >> s;
    if (n > 500) return 0;

    vector<int> stkA, stkB;
    for (int i = 0; i < n + n; ++i) {
        if (s[i] == 'B') 
            stkB.pb(i);
        else
            lft[SZ(stkA)] = SZ(stkB), stkA.pb(i);
    }
    s.clear();
    vector<int> plA, plB;
    int cnt = 0;
    for (int i = 0, j = 0; i < n; ++i) {
        while (j < n && cnt > 0 && stkB[j] < stkA[i]) {
            plB.pb(SZ(s)), s.pb('B');
            ++j, --cnt;
        }
        plA.pb(SZ(s)), s.pb('A'), ++cnt;
        ans += lft[i] - SZ(plB);
        lft[i] = SZ(plB);
    }
    while (SZ(s) < n + n)
        plB.pb(SZ(s)), s.pb('B');

    vector<node> grp;

    node cur;
    cur.first = -1;
    for (int i = 0; i < n; ++i) {
        if (cur.first == -1 || plA[i] > plB[cur.first]) {
            if (cur.first != -1)
                grp.pb(cur);
            cur.first = i;
            cur.sz = 1;
            cur.sum = lft[i];
        }
        else {
            cur.sz += 1;
            cur.sum += lft[i];
        }
    }
    grp.pb(cur);
    const ll INF = 1e18;
    vector<vector<ll>> dp(k + 1, vector<ll>(SZ(grp) + 1, INF));
    ll fin = INF;
    dp[0][0] = 0;
    for (int i = 1; i <= k; ++i) {
        for (int j = 1; j <= SZ(grp); ++j) {
            dp[i][j] = min(dp[i][j], dp[i - 1][j - 1]);
            int sz = grp[j - 1].sz;
            ll sum = grp[j - 1].sum;
            for (int p = j - 1; p > 0; --p) {
                dp[i][j] = min(dp[i][j], dp[i - 1][p - 1] + sum - sz * grp[p - 1].first);
                sz += grp[p - 1].sz;
                sum += grp[p - 1].sum;
            }
        }
        fin = min(fin, dp[i][SZ(grp)]);
    }

    cout << ans + fin << "\n";

    /*list<node> grp;
    typedef pair<ll, int> pr;
    priority_queue<pr, vector<pr>, greater<pr>> pq;
    node cur;
    cur.first = -1;
    for (int i = 0; i < n; ++i) {
        if (cur.first == -1 || plA[i] > plB[cur.first]) {
            if (cur.first != -1)
                grp.pb(cur);
            cur.first = i;
            cur.sz = 1;
            cur.sum = lft[i];
        }
        else {
            cur.sz += 1;
            cur.sum += lft[i];
        }
    }
    grp.pb(cur);

    auto cal = [&](list<node>::iterator it) {
        if (next(it) == grp.end()) return -1LL;
        ll cst;
        cst = next(it)->sum - it->first * next(it)->sz;
        return cst;
    };

    auto rm = [&](list<node>::iterator it) {
        it->sz += next(it)->sz;
        it->sum += next(it)->sz * it->first;
        arr[next(it)->first] = grp.end();
        grp.erase(next(it));
        if (next(it) != grp.end())
            pq.push(pr(cal(it), it->first));
        if (it != grp.begin())
            pq.push(pr(cal(prev(it)), prev(it)->first));
    };

    for (int i = 0; i < n; ++i)
        arr[i] = grp.end();

    for (auto it = grp.begin(); next(it) != grp.end(); ++it) {
        arr[it->first] = it;
        pq.push(pr(cal(it), it->first));
    }

    cerr << s << "\n";
    for (int i = 0; i < n; ++i)
        cerr << plA[i] << " ";
    cerr << endl;
    for (int i = 0; i < n; ++i)
        cerr << plB[i] << " ";
    cerr << endl;

    cerr << ans << "\n";

    while (!pq.empty() && SZ(grp) > k) {
        auto [cst, first] = pq.top();
        pq.pop();
        if (arr[first] == grp.end() || cst != cal(arr[first])) continue;
        ans += cst;
        rm(arr[first]);
    }
    assert(SZ(grp) <= k);

    cout << ans << "\n";*/
}

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