Submission #1210448

#	Time	Username	Problem	Language	Result	Execution time	Memory
1210448		badge881	Rainforest Jumps (APIO21_jumps)	C++20	100 / 100	503 ms	50560 KiB

jumps

#include <bits/stdc++.h>

using namespace std;

const int MAXN = 2e5 + 11;

int n;
int a[MAXN];
int l[MAXN][20], r[MAXN][20], mx[MAXN][20];

stack<int> s;

void init(int N, std::vector<int> H)
{
    n = N;
    for (int i = 0; i < n; i++)
        a[i] = H[i];
    for (int i = 0; i < n; i++)
    {
        while (s.size() && a[s.top()] < a[i])
            s.pop();
        l[i][0] = (s.empty() ? i : s.top()), s.push(i);
    }
    for (int i = n - 1; i >= 0; i--)
    {
        while (s.size() && a[s.top()] < a[i])
            s.pop();
        r[i][0] = (s.empty() ? i : s.top()), s.push(i);
    }
    for (int i = 0; i < n; i++)
        mx[i][0] = (a[l[i][0]] > a[r[i][0]] ? l[i][0] : r[i][0]);
    for (int k = 1; k < 20; k++)
        for (int i = 0; i < n; i++)
            l[i][k] = l[l[i][k - 1]][k - 1], r[i][k] = r[r[i][k - 1]][k - 1], mx[i][k] = mx[mx[i][k - 1]][k - 1];
}

int minimum_jumps(int A, int B, int C, int D)
{
    if (r[B][0] > D)
        return -1;
    if (r[B][0] >= C)
        return 1;
    int p = B + 1;
    for (int i = 19; i >= 0; i--)
        if (r[p][i] < C)
            p = r[p][i];
    if (r[p][0] < C || r[p][0] > D)
        return -1;
    int s = B, ans = 0;
    for (int i = 19; i >= 0; i--)
        if (a[l[s][i]] < a[p] && l[s][i] >= A)
            s = l[s][i];
    if (l[s][0] >= A && C <= r[l[s][0]][0] && r[l[s][0]][0] <= D)
        return 1;
    for (int i = 19; i >= 0; i--)
        if (a[mx[s][i]] <= a[p])
            s = mx[s][i], ans += (1 << i);
    if (s == p)
        return ans + 1;
    if (C <= r[s][0] && r[s][0] <= D)
        return ans + 1;
    if (C <= r[l[s][0]][0] && r[l[s][0]][0] <= D)
        return ans + 2;
    for (int i = 19; i >= 0; i--)
        if (r[s][i] < C)
            s = r[s][i], ans += (1 << i);
    s = r[s][0], ans++;
    if (C <= s && s <= D)
        return ans;
    else
        return -1;
}

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 13 / 13
• Subtask 4: 12 / 12
• Subtask 5: 23 / 23
• Subtask 6: 21 / 21
• Subtask 7: 19 / 19