Submission #769308

#	Time	Username	Problem	Language	Result	Execution time	Memory
769308		dxz05	Rainforest Jumps (APIO21_jumps)	C++17	23 / 100	927 ms	33304 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>

using namespace std;

const int MaxN = 200000;
const int Log = 18;

int N;
int low[MaxN][Log], high[MaxN][Log];
int lf[MaxN], rg[MaxN];

vector<int> H;

void init(int _N, vector<int> _H) {
    N = _N, H = _H;

    stack<int> st;
    for (int i = 0; i < N; i++){
        while (!st.empty() && H[st.top()] < H[i]) st.pop();
        lf[i] = (st.empty() ? -1 : st.top());
        st.push(i);
    }

    while (!st.empty()) st.pop();

    for (int i = N - 1; i >= 0; i--){
        while (!st.empty() && H[st.top()] < H[i]) st.pop();
        rg[i] = (st.empty() ? -1 : st.top());
        st.push(i);
    }

    memset(low, -1, sizeof(low));
    memset(high, -1, sizeof(high));

    for (int i = 0; i < N; i++){
        int l = lf[i], r = rg[i];
        if (l == -1 && r == -1) continue;

        if (l != -1 && r != -1){
            low[i][0] = (H[l] < H[r] ? l : r);
            high[i][0] = (H[l] > H[r] ? l : r);
        } else {
            low[i][0] = high[i][0] = (l != -1 ? l : r);
        }

    }

    for (int j = 1; j < Log; j++){
        for (int i = 0; i < N; i++){
            if (low[i][j - 1] != -1){
                low[i][j] = low[low[i][j - 1]][j - 1];
            }
            if (high[i][j - 1] != -1){
                high[i][j] = high[high[i][j - 1]][j - 1];
            }
        }
    }

}

int minimum_jumps(int A, int B, int C, int D) {
    if (A != B || C != D) return 0;
    if (H[A] > H[C]) return -1;

    int ans = 0;

    int v = A;
    for (int i = Log - 1; i >= 0; i--){
        int u = high[v][i];
        if (u != -1 && H[u] <= H[C]){
            ans += 1 << i;
            v = u;
        }
    }

    for (int i = Log - 1; i >= 0; i--){
        int u = low[v][i];
        if (u != -1 && H[u] <= H[C]){
            ans += 1 << i;
            v = u;
        }
    }

    return (C <= v && v <= D ? ans : -1);
}

• Subtask 1: 0 / 4
• Subtask 2: 0 / 8
• Subtask 3: 0 / 13
• Subtask 4: 0 / 12
• Subtask 5: 23 / 23
• Subtask 6: 0 / 21
• Subtask 7: 0 / 19