Submission #569942

#	Time	Username	Problem	Language	Result	Execution time	Memory
569942		toastifishi	Rainforest Jumps (APIO21_jumps)	C++14	100 / 100	1084 ms	50592 KiB

jumps

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e5 + 5;
const int MAXLG = 20;
int n, heights[MAXN];
int L[MAXN][MAXLG], R[MAXN][MAXLG], high[MAXN][MAXLG];

void init(int N, vector<int> H) {
    n = N;
    heights[0] = heights[n + 1] = 1e9;
    for(int i = 0; i < n; i++) heights[i + 1] = H[i];
    vector <int> ii; ii.push_back(0);
    for(int i = 1; i <= n; i++) {
        while(heights[ii.back()] < heights[i]) ii.pop_back();
        L[i][0] = ii.back();
        ii.push_back(i);
    }
    ii.clear(); ii.push_back(n + 1);
    for(int i = n; i >= 1; i--) {
        while(heights[ii.back()] < heights[i]) ii.pop_back();
        R[i][0] = ii.back();
        ii.push_back(i);
        high[i][0] = ((heights[L[i][0]] > heights[R[i][0]] ? L[i][0] : R[i][0]));
    }
    R[n + 1][0] = n + 1;
    for(int p = 1; p <= 19; p++) {
        R[n + 1][p] = n + 1;
        for(int i = 1; i <= n; i++) {
            L[i][p] = L[L[i][p - 1]][p - 1];
            R[i][p] = R[R[i][p - 1]][p - 1];
            high[i][p] = high[high[i][p - 1]][p - 1];
        }
    }
}
int minimum_jumps(int A, int B, int C, int D) {
    A++, B++, C++, D++;
    int furthest = B;
    for(int i = 19; i >= 0; i--) {
        if(R[furthest][i] < C) furthest = R[furthest][i];
    }
    if(furthest == B) {
        if(R[B][0] <= D) return 1;
    }
    int st = B;
    for(int i = 19; i >= 0; i--) {
        if(L[st][i] >= A && heights[L[st][i]] < heights[furthest]) st = L[st][i];
    }
    if(L[st][0] >= A && R[L[st][0]][0] <= D) return 1;
    int cur = st, ans = 0;
    for(int i = 19; i >= 0; i--) {
        if(heights[high[cur][i]] <= heights[furthest]) {
            cur = high[cur][i];
            ans += 1 << i;
        }
    }
    if(R[cur][0] >= C && R[cur][0] <= D) return ans + 1;
    if(L[cur][0] != 0 && R[L[cur][0]][0] <= D) return ans + 2;
    for(int i = 19; i >= 0; i--) {
        if(R[cur][i] < C) {
            cur = R[cur][i];
            ans += 1 << i;
        }
    }
    if(R[cur][0] <= D) return ans + 1;
    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