Submission #1296438

#	Time	Username	Problem	Language	Result	Execution time	Memory
1296438		idk_anything_i_guess	Split the sequence (APIO14_sequence)	C++20	0 / 100	1 ms	340 KiB

sequence

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

int n, k;
vector<ll> a, s;
vector<ll> dp_prev, dp_cur;
vector<vector<int>> parent;  // parent[t][i] = best j for dp[t][i]

void solve(int t, int l, int r, int optL, int optR) {
    if (l > r) return;
    int mid = (l + r) / 2;

    pair<ll,int> best = {LLONG_MIN, -1};

    for (int j = optL; j <= min(mid-1, optR); j++) {
        ll val = dp_prev[j] + s[j] * (s[mid]-s[j]);
        if (val > best.first) {
            best = {val, j};
        }
    }

    dp_cur[mid] = best.first;
    parent[t][mid] = best.second;

    int opt = best.second;

    solve(t, l, mid-1, optL, opt);
    solve(t, mid+1, r, opt, optR);
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n >> k;
    a.assign(n+1, 0);
    s.assign(n+1, 0);
    for (int i=1; i<=n; i++) cin >> a[i];
    for (int i=1; i<=n; i++) s[i] = s[i-1]+a[i];

    dp_prev.assign(n+1, 0);
    dp_cur.assign(n+1, 0);
    parent.assign(k+1, vector<int>(n+1, -1));

    for (int t=1; t<=k; t++) {
        solve(t, 1, n, 1, n-1);  // start optL from 1 to enforce first cut ≥1
        dp_prev = dp_cur;
    }

    ll answer = dp_prev[n];

    // Reconstruct split positions
    vector<int> cuts(k);
    int pos = n;
    for (int t = k; t >= 1; t--) {
        int j = parent[t][pos];
        cuts[t-1] = max(1, j);  // ensure splits are in [1, n-1]
        pos = j;
    }

    // Output
    cout << answer << "\n";
    for (int i=0; i<k; i++) {
        if (i>0) cout << " ";
        cout << cuts[i];
    }
    cout << "\n";
}

• Subtask 1: 0 / 11
• Subtask 2: 0 / 11
• Subtask 3: 0 / 11
• Subtask 4: 0 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29