krsu 3408 (whos code is this?)

#include "bits/stdc++.h"
using namespace std;

#define ar array
typedef long long ll;
#define int ll

const int N = 2e4 + 5;
const int M = 15;
int dp[N], tp[N], h[N], mx[N][M];

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    int n, k;
    cin >> n >> k;
    for (int i = 1; i <= n; i++) {
        cin >> h[i];
        dp[i] = max(dp[i - 1], h[i]);
        mx[i][0] = h[i];
    }
    for (int i = 1; i <= n; i++) {
        dp[i] *= i;
    }

    for (int j = 1; j < M; j++) {
        for (int i = 1; i + (1 << (j - 1)) <= n; i++) {
            mx[i][j] = max(mx[i][j - 1], mx[i + (1 << (j - 1))][j - 1]);
        }
    }

    auto get = [&](int l, int r) {
        int lg = __lg(r - l + 1);
        return max(mx[l][lg], mx[r - (1 << lg) + 1][lg]);
    };

    function<void(int, int, int, int)> go = [&](int l, int r, int l_, int r_) {
        if (l > r)
            return;
        int m = (l + r) >> 1, pos = l_;
        for (int j = l_; j <= min(r_, m - 1); j++) {
            int v = get(j + 1, m) * 1ll * (m - j) + dp[j];
            if (v <= tp[m]) {
                tp[m] = v;
                pos = j;
            }
        }

        go(l, m - 1, l_, pos);
        go(m + 1, r, pos, r_);
    };

    //~ for(int i=1;i<=n;i++) cout<<dp[i]<<" ";
    // ~ cout<<"\n";

    for (int j = 1; j < k; j++) {
        memset(tp, 63, sizeof tp);
        go(1, n, 1, n);
        swap(tp, dp);
    }

    cout << dp[n] - accumulate(h + 1, h + n + 1, 0) << "\n";
}
/*

7 3
6 4 1 5 3 2 2

4 2
6 1 7 4

*/