Submission #541809

#	Time	Username	Problem	Language	Result	Execution time	Memory
541809		zxcvbnm	K blocks (IZhO14_blocks)	C++14	100 / 100	842 ms	6192 KiB

blocks

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

constexpr int nax = 1e5 + 5;
constexpr int kax = 105;
constexpr ll INF = 1e12 + 5;

#define int ll

struct St {
    int n;
    vector<int> tree;
    void build(const vector<int>& vec, bool naujas=false) {
        if (naujas) {
            n = 1;
            while(n < (int) vec.size()) {
                n *= 2;
            }

            tree.assign(2*n, 0LL);
        }

        build_r(vec, 0, 0, n);
    }

    void build_r(const vector<int>& vec, int idx, int l, int r) {
        if (r - l == 1) {
            if (l < vec.size()) {
                tree[idx] = vec[l];
            }
            return;
        }

        int mid = (l + r) / 2;
        build_r(vec, 2*idx+1, l, mid);
        build_r(vec, 2*idx+2, mid, r);

        tree[idx] = min(tree[2*idx+1], tree[2*idx+2]);
    }

    int mx(int L, int R) {
        return mx_r(0, 0, n, L, R);
    }

    int mx_r(int idx, int l, int r, int L, int R) {
        if (l >= R || L >= r) return INF;
        if (l >= L && R >= r) {
            return tree[idx];
        }

        int mid = (l + r) / 2;
        auto s1 = mx_r(2*idx+1, l, mid, L, R);
        auto s2 = mx_r(2*idx+2, mid, r, L, R);

        return min(s1, s2);
    }
};

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, k;
    cin >> n >> k;
    assert(n < nax);

    vector<int> a(n);
    for(int& i : a) {
        cin >> i;
    }

    if (n == k) {
        cout << accumulate(a.begin(), a.end(), 0LL);
        exit(0);
    }

    int last[n];
    last[0] = -1;
    for(int i = 1; i < n; i++) {
        int idx = i-1;
        while(idx >= 0 && a[idx] <= a[i]) {
            idx = last[idx];
        }
        last[i] = idx;

//        cout << last[i]+1 << " " << i-1 << "\n";
    }

    vector<int> praitas(n, 0);
    St st;
    st.build(praitas, true);

    for(int curr_k = 1; curr_k <= k; curr_k++) {

        vector<int> dabartinis(n, INF);
        if (curr_k == 1) {
            dabartinis[0] = a[0];
            for(int i = 1; i < n; i++) {
                dabartinis[i] = max(a[i], dabartinis[i-1]);
            }
        }
        else {
            for(int i = curr_k-1; i < n; i++) {
                if (last[i] >= 0) {
                    dabartinis[i] = min(dabartinis[i], dabartinis[last[i]]);
                }

                dabartinis[i] = min(dabartinis[i], (i == last[i]+1 ? praitas[i-1] : st.mx(last[i]+1, i)) + a[i]);

//                cout << i << " " << curr_k << ": " << dabartinis[i] << " " << last[i] << "\n";
     //            cout << last[i]+1 << " " << i-1 << "\n";
            }
        }

        st.build(dabartinis);
        praitas = dabartinis;
    }

    cout << praitas.back() << "\n";

//    for(int i = 0; i < n; i++) {
//        cout << last[i] << " ";
//    }
    return 0;
}

/*

3 2
3 15 7

11 2
15 11 1 1 1 9 19 2 2 3 100

15 4
7 3 2 4 8 4 9 10 5 5 1 2 3 4 5 11

6 3
1 8 5 2 3 7
*/

Compilation message (stderr)

blocks.cpp: In member function 'void St::build_r(const std::vector<long long int>&, ll, ll, ll)':
blocks.cpp:29:19: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |             if (l < vec.size()) {
      |                 ~~^~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 18 / 18
• Subtask 3: 21 / 21
• Subtask 4: 47 / 47