Submission #1199762

#	Time	Username	Problem	Language	Result	Execution time	Memory
1199762		adiyer	Rainforest Jumps (APIO21_jumps)	C++20	0 / 100	128 ms	40344 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;

int val(int i){
    return (i == -1 ? n + 1 : a[i]);
}

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() ? -1 : 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() ? -1 : s.top()), s.push(i);
    }
    for(int i = 0; i < n; i++){
        if(l[i][0] == -1 && r[i][0] == -1) mx[i][0] = -1;
        else if(r[i][0] != -1 && (l[i][0] == -1 || a[r[i][0]] > a[l[i][0]])) mx[i][0] = r[i][0];
        else mx[i][0] = l[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;
    for(int i = 19; i >= 0; i--)
        if(r[p][i] < C)
            p = r[p][i];
    if(r[p][0] > D) return -1;
    int s = B, t = 0, ans = 0;
    for(int i = 19; i >= 0; i--)
        if(val(l[s][i]) < a[p] && l[s][i] >= A)
            s = l[s][i];
    for(int i = 19; i >= 0; i--){
        if(l[s][0] != -1 && a[l[s][0]] > a[p] && r[l[s][0]][0] <= D){
            if(l[s][0] >= A) return ans + 1;
            else return ans + 2;
        }
        if(val(mx[s][i]) < a[p]) s = mx[s][i], ans |= (1 << i);
    }
    return ans + 2;
}

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