Submission #1296440

#	Time	Username	Problem	Language	Result	Execution time	Memory
1296440		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;

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,0,n-1);
        dp_prev = dp_cur;
    }

    ll answer = dp_prev[n];

    // Reconstruct splits
    vector<int> cuts;
    int pos = n;
    for(int t=k; t>=1; t--){
        int j = parent[t][pos];
        if(j > 0) cuts.push_back(j);  // only actual splits
        pos = j;
    }
    reverse(cuts.begin(), cuts.end());

    // Output
    cout << answer << "\n";
    for(int i=0;i<(int)cuts.size();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