Submission #676367

#	Time	Username	Problem	Language	Result	Execution time	Memory
676367		benjaminkleyn	Split the sequence (APIO14_sequence)	C++17	0 / 100	43 ms	82104 KiB

sequence

#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;

int N, K, a[100001];
ll pref[100001] = {0};
ll dp[100001][2] = {0};
int last_split[100001][202];

int cht[100001], fr = 0, bk = -1;

#define m(j) (pref[j])
#define c(j) (dp[j][0]-pref[j]*pref[N])

inline bool bad(const int &x, const int &y, const int &z)
{
    return (c(z) - c(y)) * (m(z) - m(x)) <= (c(z) - c(x)) * (m(z) - m(y));
}

inline ll eval(const int &i, const ll &x)
{
    return m(i) * x + c(i);
}
 
int main()
{
    cin.tie(0)->sync_with_stdio(0);

    cin >> N >> K;
    for (int i = 1; i <= N; i++)
    {
         cin >> a[i];
         pref[i] = pref[i-1] + a[i];
    }
 
    for (int k = 1; k <= K + 1; k++)
    {
        fr = 0, bk = -1;
        for (int i = 1; i <= N; i++)
        {
            while (fr < bk && bad(cht[bk-1], cht[bk], i-1))
                bk--;

            cht[++bk] = i-1;

            while (fr < bk && eval(cht[fr], pref[i]) <= eval(cht[fr+1], pref[i]))
                fr++;

            dp[i][1] = eval(cht[fr], pref[i]) + pref[i] * (pref[N] - pref[i]);
            last_split[i][k] = cht[fr];
        }
        for (int i = 1; i <= N; i++)
            dp[i][0] = dp[i][1];
    }

    cout << dp[N][0] << '\n';
    int i = N;
    do
    {
        i = last_split[i][K+1];
        cout << i << ' ';
    } while (--K);
    cout << '\n';
 
    return 0;
}

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