Submission #1021043

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021043		12345678	Rainforest Jumps (APIO21_jumps)	C++17	100 / 100	950 ms	45116 KiB

jumps

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

using namespace std;

const int nx=2e5+5, kx=18;

int l[kx][nx], r[kx][nx], g[kx][nx];

void init(int N, std::vector<int> H) {
    H.push_back(INT_MIN);
    stack<int> s;
    for (int i=0; i<=N; i++) l[0][i]=r[0][i]=g[0][i]=N;
    for (int i=0; i<N; i++)
    {
        while (!s.empty()&&H[s.top()]<H[i]) s.pop();
        if (!s.empty()) l[0][i]=s.top();
        s.push(i);
    }
    while (!s.empty()) s.pop();
    for (int i=N-1; i>=0; i--)
    {
        while (!s.empty()&&H[s.top()]<H[i]) s.pop();
        if (!s.empty()) r[0][i]=s.top();
        s.push(i);
    }
    for (int i=0; i<N; i++) g[0][i]=(H[l[0][i]]>H[r[0][i]])?l[0][i]:r[0][i];
    for (int i=1; i<kx; i++) for (int j=0; j<=N; j++) l[i][j]=l[i-1][l[i-1][j]], r[i][j]=r[i-1][r[i-1][j]], g[i][j]=g[i-1][g[i-1][j]];
}

int minimum_jumps(int A, int B, int C, int D) {
    int opt=B, ans=0;
    for (int i=kx-1; i>=0; i--) if (l[i][opt]>=A&&r[0][l[i][opt]]<=D) opt=l[i][opt];
    if (C<=r[0][opt]&&r[0][opt]<=D) return 1;
    for (int i=kx-1; i>=0; i--) if (r[0][g[i][opt]]<C) ans+=(1<<i), opt=g[i][opt];
    if (r[0][g[0][opt]]<=D) return ans+2;
    for (int i=kx-1; i>=0; i--) if (r[i][opt]<C) ans+=(1<<i), opt=r[i][opt];
    if (r[0][opt]<C||r[0][opt]>D) return -1;
    else return ans+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