Submission #1201877

#	Time	Username	Problem	Language	Result	Execution time	Memory
1201877		aykhn	Rainforest Jumps (APIO21_jumps)	C++20	48 / 100	801 ms	67048 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];
int sp[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;
    sp[0][0][i] = prv[i], sp[1][0][i] = nxt[i];
    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]];
      }
    }
    for (int i = 1; i < LOG; i++)
    {
      for (int j = 0; j < N; j++)
      {
        if (sp[_][i - 1][j] == -1) 
        {
          sp[_][i][j] = -1;
          continue;
        }
        sp[_][i][j] = sp[_][i - 1][sp[_][i - 1][j]];
      }
    }
  }
}

int dist(int A, int C)
{
  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;
}

int minimum_jumps(int A, int B, int C, int D) 
{
  int X = C;
  for (int i = LOG - 1; i >= 0; i--)
  {
    if (sp[1][i][X] == -1 || sp[1][i][X] > D) continue;
    X = sp[1][i][X];
  }
  for (int i = LOG - 1; i >= 0; i--)
  {
    if (sp[0][i][B] == -1 || sp[0][i][B] < A) continue;
    if (dist(sp[0][i][B], X) == -1) continue;
    B = sp[0][i][B];
  }
  if (!(sp[0][0][B] == -1 || sp[0][0][B] < A || dist(sp[0][0][B], X) == -1)) B = sp[0][0][B];
  for (int i = LOG - 1; i >= 0; i--)
  {
    if (sp[1][i][C] == -1 || sp[1][i][C] > D) continue;
    if (dist(B, sp[1][i][C]) != -1) continue;
    C = sp[1][i][C];
  }
  if (!(sp[1][0][C] == -1 || sp[1][0][C] > D || dist(B, sp[1][0][C]) == -1) && dist(B, C) == -1) C = sp[1][0][C];
  return dist(B, C);
}

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