Submission #1233064

#	Time	Username	Problem	Language	Result	Execution time	Memory
1233064		LucaLucaM	Rainforest Jumps (APIO21_jumps)	C++20	0 / 100	4017 ms	5152 KiB

jumps

#include "jumps.h"

#include <iostream>
#include <vector>
#include <algorithm>
#include <cassert>

std::vector<int> prev, next;
std::vector<int> to;

void init(int n, std::vector<int> p) {
  std::vector<int> st;
  prev.resize(n);
  next.resize(n);
  for (int i = 0; i < n; i++) {
    while (!st.empty() && p[st.back()] < p[i]) {
      st.pop_back();
    }
    prev[i] = st.empty()? -1 : st.back();
    st.push_back(i);
  }
  st.clear();
  for (int i = n - 1; i >= 0; i--) {
    while (!st.empty() && p[st.back()] < p[i]) {
      st.pop_back();
    }
    next[i] = st.empty()? -1 : st.back();
    st.push_back(i);
  }
  st.clear();

  to.resize(n);
  for (int i = 0; i < n; i++) {
    if (prev[i] == -1) {
      to[i] = next[i];
    } else if (next[i] == -1) {
      to[i] = prev[i];
    } else {
      if (p[prev[i]] < p[next[i]]) {
        to[i] = prev[i];
      } else {
        to[i] = next[i];
      }
    }
  }
}

int minimum_jumps(int A, int B, int C, int D) {
  int ret = 1e9;
  for (int i = A; i <= B; i++) {
    int u = i;
    int dist = 0;
    std::vector<int> vis;
    while (u != -1) {
      vis.push_back(u);
      if (C <= u && u <= D) {
        break;
      }
      u = to[u];
    }
    if (u != -1) {
      dist = (int) vis.size() - 1;
      for (int i = 0; i + 2 < (int) vis.size(); i++) {
        int u = vis[i];
        if (to[to[u]] == (prev[u] ^ next[u] ^ to[u])) {
          i++;
          dist--;
        }
      }
      ret = std::min(ret, dist);
    }
  }
  return ret == 1e9? -1 : ret;
}

• 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