Submission #1304981

#	Time	Username	Problem	Language	Result	Execution time	Memory
1304981		chithanhnguyen	K blocks (IZhO14_blocks)	C++20	100 / 100	212 ms	199088 KiB

blocks

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

// #define int long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) ((1ll << (x)))

#define debug(a, l, r) for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';

const int MAXN = 1e5 + 5;
const int MAXK = 500 + 5;
const long long INF  = 1e9 + 5;
int n, k, a[MAXN], dp[MAXN][MAXK];

void solve() {
    for (int i = 0; i < MAXN; ++i)
        for (int j = 0; j < MAXK; ++j)
            dp[i][j] = INF;

    cin >> n >> k;
    for (int i = 1; i <= n; ++i) cin >> a[i];
    dp[0][0] = 0;
    // Get min at dp[j - 1][j - 1];
    
    int cur = 0;
    for (int i = 1; i <= n; ++i) {
        cur = max(cur, a[i]);
        dp[i][1] = cur;
    }

    vector<pii> st;
    for (int j = 2; j <= k; ++j) {
        for (int i = j; i <= n; ++i) {
            // int mx = 0;
            // for (int t = j; t <= i; ++t) mx = max(mx, a[t]);
            // dp[i][j] = dp[j - 1][j - 1] + mx;

            int cand = dp[i - 1][j - 1];
            while (!st.empty() && a[st.back().se] <= a[i]) {
                cand = min(cand, st.back().fi);
                st.pop_back();
            }

            dp[i][j] = min(dp[st.empty() ? 0 : st.back().se][j], cand + a[i]);
            st.push_back({cand, i});

            // int mx = a[i];
            // // cout << "State " << i << ' ' << j << ": \n";
            // int mii = 0, mij = 0;
            // for (int pre = i - 1; pre >= 0; --pre) {
            //     if (dp[pre][j - 1] + mx < dp[i][j]) {
            //         mii = pre; mij = j - 1;
            //     }
            //     dp[i][j] = min(dp[i][j], dp[pre][j - 1] + mx);
            //     // cout << "pre = " << pre << ": " << dp[pre][j - 1] + mx << '\n';
            //     mx = max(mx, a[pre]);
            // }
            // // cout << "Minimum at " << mii << ' ' << mij << '\n';
        }
        st.clear();
    }

    cout << dp[n][k];
}

signed main() {
    #ifdef NCTHANH
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr); cout.tie(nullptr);

    solve();

    return 0;
}

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