Submission #1101320

#	Time	Username	Problem	Language	Result	Execution time	Memory
1101320		blackslex	Rainforest Jumps (APIO21_jumps)	C++17	0 / 100	212 ms	27976 KiB

jumps

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

using namespace std;

const int MxN = 2e5 + 5, K = 19;
int n, l[MxN], r[MxN], dp[K][MxN], dp2[K][MxN];
vector<int> h;

void init(int N, std::vector<int> H) {
  n = N; h = H;
  stack<int> st;
  for (int i = 0; i < n; i++) {
    l[i] = -1;
    while (!st.empty() && h[i] > h[st.top()]) st.pop();
    if (!st.empty()) l[i] = st.top();
    st.emplace(i);
  }
  for (int i = 0; i < n; i++) dp[0][i] = (~l[i] ? l[i] : i);
  while (!st.empty()) st.pop();
  for (int i = n - 1; i >= 0; i--) {
    r[i] = -1;
    while (!st.empty() && h[i] > h[st.top()]) st.pop();
    if (!st.empty()) r[i] = st.top();
    st.emplace(i);
  }
  for (int i = 0; i < n; i++) dp2[0][i] = (~r[i] ? r[i] : i);
  for (int i = 1; i < K; i++) {
    for (int j = 0; j < n; j++) {
      dp[i][j] = dp[i - 1][dp[i - 1][j]];
      dp2[i][j] = dp2[i - 1][dp2[i - 1][j]];
    }
  }
}

int minimum_jumps(int A, int B, int C, int D) {
  int ans = 1e9;
  int cnt = 0;
  int st = A, ed = C;
  while (1) {
    int cst = st;
    for (int i = K - 1; i >= 0; i--) {
      if (h[dp2[i][st]] < h[ed]) st = dp2[i][st], cnt += (1 << i);
    }
    if (dp2[0][st] == ed) {cnt++; ans = min(ans, cnt); break;}
    for (int i = K - 1; i >= 0 ; i--) {
      if (h[dp[i][st]] < h[ed]) st = dp[i][st], cnt += (1 << i);
    }
    if (dp[0][st] == ed) {cnt++; ans = min(ans, cnt); break;}
    if (cst == st) break;
  }
  cnt = 0; st = A; ed = C;
  while (1) {
    int cst = st;
    for (int i = K - 1; i >= 0; i--) {
      if (h[dp[i][st]] < h[ed]) st = dp[i][st], cnt += (1 << i);
    }
    if (dp[0][st] == ed) {cnt++; ans = min(ans, cnt); break;}
    for (int i = K - 1; i >= 0 ; i--) {
      if (h[dp2[i][st]] < h[ed]) st = dp2[i][st], cnt += (1 << i);
    }
    if (dp2[0][st] == ed) {cnt++; ans = min(ans, cnt); break;}
    if (cst == st) break;
  }
  return (ans == 1e9 ? -1 : ans);
}

• 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