Submission #1282173

#	Time	Username	Problem	Language	Result	Execution time	Memory
1282173		khanhphucscratch	Rainforest Jumps (APIO21_jumps)	C++20	23 / 100	423 ms	35628 KiB

jumps

#include "jumps.h"
#include<bits/stdc++.h>
using namespace std;
int n, h[200005], le[200005], ri[200005], jump_max[200005][20], jumpri[200005][20];
void init(int N, vector<int> H) {
    n = N;
    for(int i = 0; i < n; i++) h[i+1] = H[i];
    h[0] = h[n+1] = 1e9; ri[n+1] = n+1;
    for(int i = 1; i <= n; i++){
        le[i] = i-1;
        while(h[le[i]] < h[i]) le[i] = le[le[i]];
    }
    for(int i = n; i >= 1; i--){
        ri[i] = i+1;
        while(h[ri[i]] < h[i]) ri[i] = ri[ri[i]];
    }
    for(int i = 1; i <= n; i++){
        if(h[le[i]] > h[ri[i]]) jump_max[i][0] = le[i];
        else jump_max[i][0] = ri[i];
        jumpri[i][0] = ri[i];
    }
    jumpri[n+1][0] = jump_max[n+1][0] = n+1;
    for(int j = 1; j <= 19; j++){
        for(int i = 0; i <= n+1; i++){
            jump_max[i][j] = jump_max[jump_max[i][j-1]][j-1];
            jumpri[i][j] = jumpri[jumpri[i][j-1]][j-1];
        }
    }
}

int minimum_jumps(int l1, int r1, int l2, int r2) {
    l1++; r1++; l2++; r2++;
    //We have l1 = r1 and l2 = r2
    //First check if it's possible
    int u = l1;
    for(int i = 19; i >= 0; i--) if(jumpri[u][i] <= l2) u = jumpri[u][i];
    if(u < l2) return -1;
    //Now find the best answer
    int ans = 0; u = l1;
    for(int i = 19; i >= 0; i--) if(h[jump_max[u][i]] < h[l2]){
        u = jump_max[u][i]; ans += (1 << i);
    }
    for(int i = 19; i >= 0; i--) if(jumpri[u][i] <= l2){
        u = jumpri[u][i]; ans += (1 << i);
    }
    return ans;
}

• 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