Submission #538933

#	Time	Username	Problem	Language	Result	Execution time	Memory
538933		Monarchuwu	Triple Jump (JOI19_jumps)	C++17	46 / 100	489 ms	72608 KiB

jumps

#include<iostream>
#include<algorithm>
#include<numeric>
using namespace std;
typedef long long ll;

const int N = 5e5 + 5, N2 = 5000 + 3, inf = 1e9 + 7;
int n, lg[N];
int a[19][N];

void build() {
    for (int j = 0; j < 18; ++j)
        for (int i = 1; i + (2 << j) - 1 <= n; ++i)
            a[j + 1][i] = max(a[j][i], a[j][i + (1 << j)]);

    lg[1] = 0;
    for (int i = 2; i <= n; ++i) lg[i] = lg[i >> 1] + 1;
}
int get(int l, int r) {
    if (r < 1 || n < l || r < l) return -inf;
    int k = lg[r - l + 1];
    return max(a[k][l], a[k][r - (1 << k) + 1]);
}

int dp[N2][N2];
void subtask12() {
    for (int i = 1; i <= n; ++i)
        for (int k = i + 2; k <= n; ++k)
            dp[i][k] = a[0][i] + get(i + 1, (i + k) >> 1) + a[0][k];

    for (int len = 3; len <= n; ++len)
        for (int i = 1, j = len; j <= n; ++i, ++j)
            dp[i][j] = max({ dp[i][j - 1], dp[i + 1][j], a[0][i] + get(i + 1, (i + j) >> 1) + a[0][j] });

    int q, l, r; cin >> q; while (q--) {
        cin >> l >> r;
        cout << dp[l][r] << '\n';
    }
}

int calc(int p1, int p2) {
    return max({ get(max(1, p1 * 2 - p2), p1 - 1), get(p1 + 1, (p1 + p2) >> 1), get(p2 * 2 - p1, n) });
}
int idx[N];
void subtask3() {
    iota(idx + 1, idx + n + 1, 1);
    sort(idx + 1, idx + n + 1, [](int i, int j) { return a[0][i] > a[0][j]; });

    int ans(-inf);
    for (int p = 1; p <= 20; ++p) {
        int i = idx[p];

        for (int j = 1; j < i; ++j)
            ans = max(ans, a[0][j] + calc(j, i) + a[0][i]);
        for (int j = i + 1; j <= n; ++j)
            ans = max(ans, a[0][i] + calc(i, j) + a[0][j]);
    }
    cout << ans << '\n';
}

int main() {
    cin.tie(NULL)->sync_with_stdio(false);
    cin >> n;
    for (int i = 1; i <= n; ++i) cin >> a[0][i];
    build();

    if (n <= 5000)
        subtask12();
    else subtask3();
}
/**  /\_/\
 *  (= ._.)
 *  / >0  \>1
**/

• Subtask 1: 5 / 5
• Subtask 2: 14 / 14
• Subtask 3: 27 / 27
• Subtask 4: 0 / 54