Submission #1201835

#	Time	Username	Problem	Language	Result	Execution time	Memory
1201835		aykhn	Rainforest Jumps (APIO21_jumps)	C++20	27 / 100	488 ms	35732 KiB

jumps

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

using namespace std;

const int MXN = 2e5 + 5;
const int LOG = 20;

int p[2][LOG][MXN];
vector<int> h;

void init(int N, vector<int> H) 
{
  h = H;
  int prv[N], nxt[N];
  {
    vector<int> st;
    for (int i = 0; i < N; i++)
    {
      while (!st.empty() && H[i] > H[st.back()]) st.pop_back();
      if (st.empty()) prv[i] = -1;
      else prv[i] = st.back();
      st.push_back(i);
    }
  }
  {
    vector<int> st;
    for (int i = N - 1; i >= 0; i--)
    {
      while (!st.empty() && H[i] > H[st.back()]) st.pop_back();
      if (st.empty()) nxt[i] = -1;
      else nxt[i] = st.back();
      st.push_back(i);
    }
  }
  for (int i = 0; i < N; i++)
  {
    p[0][0][i] = p[1][0][i] = -1;
    if (nxt[i] != -1 && prv[i] != -1)
    {
      p[0][0][i] = nxt[i], p[1][0][i] = prv[i];
      if (H[nxt[i]] > H[prv[i]]) swap(p[0][0][i], p[1][0][i]);
    }
    else p[0][0][i] = max(nxt[i], prv[i]);
  }
  for (int _ = 0; _ < 2; _++)
  {
    for (int i = 1; i < LOG; i++)
    {
      for (int j = 0; j < N; j++)
      {
        if (p[_][i - 1][j] == -1) 
        {
          p[_][i][j] = -1;
          continue;
        }
        p[_][i][j] = p[_][i - 1][p[_][i - 1][j]];
      }
    }
  }
}

int minimum_jumps(int A, int B, int C, int D) 
{
  A = max(A, B), C = min(C, D);
  int res = 0;
  for (int _ = 1; _ >= 0 && A != C; _--)
  {
    for (int i = LOG - 1; i >= 0; i--)
    {
      if (p[_][i][A] == -1) continue;
      if (h[p[_][i][A]] >= h[C]) continue;
      A = p[_][i][A];
      res += (1 << i);
    }
    if (p[_][0][A] != -1 && h[p[_][0][A]] <= h[C]) 
    {
      A = p[_][0][A];
      res++;
    }
  }
  if (A != C) return -1;
  return res;
}

• Subtask 1: 4 / 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