Submission #541626

#	Time	Username	Problem	Language	Result	Execution time	Memory
541626		aryan12	Rainforest Jumps (APIO21_jumps)	C++17	56 / 100	4058 ms	45660 KiB

jumps

#include "jumps.h"
#include <vector>
using namespace std;
#include <bits/stdc++.h>

const int MAXN = 2e5 + 5;
int DP_Min[19][MAXN], DP_Max[19][MAXN];
vector<int> INPUT;
vector<int> g[MAXN];

void init(int N, vector<int> H) {
  vector<int> L(N), R(N);
  stack<int> q;
  for(int i = 0; i < N; i++) {
    INPUT.push_back(H[i]);
    while(!q.empty() && H[q.top()] <= H[i]) {
      q.pop();
    }
    if(q.empty()) {
      L[i] = -1;
    }
    else {
      L[i] = q.top();
    }
    q.push(i);
  }
  while(!q.empty()) {
    q.pop();
  }
  for(int i = N - 1; i >= 0; i--) {
    while(!q.empty() && H[q.top()] <= H[i]) {
      q.pop();
    }
    if(q.empty()) {
      R[i] = N;
    }
    else {
      R[i] = q.top();
    }
    q.push(i);
  }
  for(int i = 0; i < N; i++) {
    if(L[i] == -1 && R[i] == N) {
      DP_Min[0][i] = -1;
      DP_Max[0][i] = -1;
    }
    else if(L[i] == -1 || R[i] == N) {
      if(L[i] == -1) {
        DP_Min[0][i] = R[i];
        DP_Max[0][i] = R[i];
      }
      else {
        DP_Min[0][i] = L[i];
        DP_Max[0][i] = L[i];
      }
    }
    else {
      if(H[L[i]] < H[R[i]]) {
        DP_Min[0][i] = L[i];
        DP_Max[0][i] = R[i];
      }
      else {
        DP_Min[0][i] = R[i];
        DP_Max[0][i] = L[i];
      }
      //DP_Min[0][i] = min(L[i], R[i]);
      //DP_Max[0][i] = max(L[i], R[i]);
    }
  }
  for(int i = 1; i < 19; i++) {
    for(int j = 0; j < N; j++) {
      if(DP_Min[i - 1][j] == -1) {
        DP_Min[i][j] = -1;
      }
      else {
        DP_Min[i][j] = DP_Min[i - 1][DP_Min[i - 1][j]];
      }
      if(DP_Max[i - 1][j] == -1) {
        DP_Max[i][j] = -1;
      }
      else {
        DP_Max[i][j] = DP_Max[i - 1][DP_Max[i - 1][j]];
      }
    }
  }
  //cout << "L[i] and R[i]\n";
  //for(int i = 0; i < N; i++) {
  //  cout << L[i] << " " << R[i] << "\n";
  //}
  //cout << DP_Min[0][4] << " " << DP_Max[0][4] << "\n";
  for(int i = 0; i < N; i++) {
    if(L[i] != -1) {
      g[i].push_back(L[i]);
    }
    if(R[i] != -1) {
      g[i].push_back(R[i]);
    }
  }
}

int minimum_jumps(int A, int B, int C, int D) {
  if(A != B || C != D) {
    queue<int> q;
    vector<int> dist(MAXN, 1e9);
    for(int i = A; i <= B; i++) {
      q.push(i);
      dist[i] = 0;
    }
    while(!q.empty()) {
      int node = q.front();
      q.pop();
      for(int i = 0; i < g[node].size(); i++) {
        if(dist[g[node][i]] == 1e9) {
          dist[g[node][i]] = dist[node] + 1;
          q.push(g[node][i]);
        }
      }
    }
    int ans = 1e9;
    for(int i = C; i <= D; i++) {
      ans = min(ans, dist[i]);
    }
    if(ans == 1e9) {
      return -1;
    }
    return ans;
  }
  int ans = 0, cur = B;
  for(int i = 18; i >= 0; i--) {
    if(DP_Max[i][cur] != -1 && INPUT[DP_Max[i][cur]] <= INPUT[C]) {
      //cout << "prev cur = " << cur << "\n";
      ans += (1 << i);
      cur = DP_Max[i][cur];
      //cout << "new cur = " << cur << ", with added answer: " << (1 << i) << "\n";
    }
  }
  for(int i = 18; i >= 0; i--) {
    if(DP_Min[i][cur] != -1 && INPUT[DP_Min[i][cur]] <= INPUT[C]) {
      ans += (1 << i);
      cur = DP_Min[i][cur];
    }
  }
  if(cur != C) return -1;
  return ans;
}

Compilation message (stderr)

jumps.cpp: In function 'int minimum_jumps(int, int, int, int)':
jumps.cpp:112:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  112 |       for(int i = 0; i < g[node].size(); i++) {
      |                      ~~^~~~~~~~~~~~~~~~

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