Submission #476815

#	Time	Username	Problem	Language	Result	Execution time	Memory
476815		Everifall	Rainforest Jumps (APIO21_jumps)	C++14	100 / 100	1562 ms	52780 KiB

jumps

#include "jumps.h"

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

const int MAXN = 2e5 + 16;
const int MLOG = 21;
int arr[MAXN],spRight[MLOG][MAXN],spLeft[MLOG][MAXN],spBest[MLOG][MAXN];

void init(int N,vector<int> H){
  arr[0] = arr[N+1] = N+8;
  for(int i=1;i<=N;i++){
    arr[i] = H[i-1];
  }
  stack<int> stkRight,stkLeft;
  for(int i=0;i<=N+1;i++){
    while((!stkRight.empty()) && arr[stkRight.top()] <= arr[i]){
      spRight[0][stkRight.top()] = i;
      stkRight.pop();
    }
    stkRight.push(i);
  }
  spRight[0][N+1] = N+1;
  for(int i=N+1;i>=0;i--){
    while((!stkLeft.empty()) && arr[stkLeft.top()] <= arr[i]){
      spLeft[0][stkLeft.top()] = i;
      stkLeft.pop();
    }
    stkLeft.push(i);
  }
  spLeft[0][0] = 0;
  for(int i=0;i<=N+1;i++){
    if(arr[spLeft[0][i]] > arr[spRight[0][i]]){
      spBest[0][i] = spLeft[0][i];
    }else{
      spBest[0][i] = spRight[0][i];
    }
  }
  for(int i=1;i<MLOG;i++){
    for(int j=0;j<=N+1;j++){
      spLeft[i][j] = spLeft[i-1][spLeft[i-1][j]];
      spRight[i][j] = spRight[i-1][spRight[i-1][j]];
      spBest[i][j] = spBest[i-1][spBest[i-1][j]];
    }
  }
}

int minRight(int idx,int C,int D){
  int res = 1;
  for(int i=MLOG;i>0;i--){
    if(spRight[i-1][idx] < C){
      idx = spRight[i-1][idx];
      res += (1 << (i-1));
    }
  }
  idx = spRight[0][idx];
  return (idx > D ? -1 : res);
}

int minimum_jumps(int A,int B,int C,int D){
  A++,B++,C++,D++;
  int curr = B;
  for(int i=MLOG;i>0;i--){
    if(spLeft[i-1][curr] >= A && spRight[0][spLeft[i-1][curr]] <= D){
      curr = spLeft[i-1][curr];
    }
  }
  int spSum = 0;
  for(int i=MLOG;i>0;i--){
    if(spRight[0][spBest[i-1][curr]] < C){
      curr = spBest[i-1][curr];
      spSum += (1 << (i-1));
    }
  }
  int res = MAXN;
  if(minRight(curr,C,D) != -1){
    res = min(res,minRight(curr,C,D)+spSum);
  }
  curr = spBest[0][curr];
  if(minRight(curr,C,D) != -1){
    res = min(res,minRight(curr,C,D)+spSum+1);
  }
  return (res == MAXN ? -1 : res);
}

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