Submission #1356410

#TimeUsernameProblemLanguageResultExecution timeMemory
1356410Desh03Rainforest Jumps (APIO21_jumps)C++20
27 / 100
278 ms45852 KiB
#include <bits/stdc++.h>

using namespace std;

mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());

const int N = 2e5, lg = 18, inf = 1e9;
int n, nxt[lg][N], prv[lg][N], g[lg][N], h[N];

void init(int N, vector<int> H) {
    n = N;
    for (int i = 0; i < n; i++) {
        h[i] = H[i];
    }
    stack<int> st;
    for (int i = 0; i < n; i++) {
        while (st.size() && h[st.top()] <= h[i]) st.pop();
        prv[0][i] = st.size() ? st.top() : -1;
        st.push(i);
    }
    while (st.size()) st.pop();
    for (int i = n - 1; i >= 0; i--) {
        while (st.size() && h[st.top()] <= h[i]) st.pop();
        nxt[0][i] = st.size() ? st.top() : -1;
        st.push(i);
    }
    for (int i = 0; i < n; i++) {
        if (nxt[0][i] == -1) g[0][i] = prv[0][i];
        else if (prv[0][i] == -1) g[0][i] = nxt[0][i];
        else g[0][i] = (h[nxt[0][i]] >= h[prv[0][i]] ? nxt[0][i] : prv[0][i]);
    }
    for (int i = 1; i < lg; i++) {
        for (int j = 0; j < n; j++) {
            prv[i][j] = prv[i - 1][j] == -1 ? -1 : prv[i - 1][prv[i - 1][j]];
            nxt[i][j] = nxt[i - 1][j] == -1 ? -1 : nxt[i - 1][nxt[i - 1][j]];
            g[i][j] = g[i - 1][j] == -1 ? -1 : g[i - 1][g[i - 1][j]];
        }
    }
}

int minimum_jumps(int a, int b, int c, int d) {
    int ans = 0;
    for (int i = lg - 1; i >= 0; i--) {
        if (g[i][b] != -1 && h[g[i][b]] < h[c]) {
            b = g[i][b];
            ans += (1 << i);
        }
    }
    if (b > c) return -1;
    for (int i = lg - 1; i >= 0; i--) {
        if (nxt[i][b] != -1 && h[nxt[i][b]] <= h[c]) {
            b = nxt[i][b];
            ans += (1 << i);
        }
    }
    return b == c ? ans : -1;
}
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