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Chief’s bot is playing an old DOS based game. There is a row of buildings of different heights arranged at each index along a number line. The bot starts at building and at a height of . You must determine the minimum energy his bot needs at the start so that he can jump to the top of each building without his energy going below zero.

Units of height relate directly to units of energy. The bot’s energy level is calculated as follows:

  • If the bot’s is less than the height of the building, his
  • If the bot’s is greater than the height of the building, his

Example

Starting with , we get the following table:

    botEnergy   height  delta
    4               2       +2
    6               3       +3
    9               4       +5
    14              3       +11
    25              2       +23
    48

That allows the bot to complete the course, but may not be the minimum starting value. The minimum starting in this case is .

Function Description

Complete the chiefHopper function in the editor below.

chiefHopper has the following parameter(s):

  • int arr[n]: building heights

Returns

  • int: the minimum starting

Input Format

The first line contains an integer , the number of buildings.

The next line contains space-separated integers , the heights of the buildings.

Constraints

  • where

Sample Input 0

5
3 4 3 2 4

Sample Output 0

4

Explanation 0

If initial energy is 4, after step 1 energy is 5, after step 2 it’s 6, after step 3 it’s 9 and after step 4 it’s 16, finally at step 5 it’s 28.
If initial energy were 3 or less, the bot could not complete the course.

Sample Input 1

3
4 4 4

Sample Output 1

4

Explanation 1

In the second test case if bot has energy 4, it’s energy is changed by (4 – 4 = 0) at every step and remains 4.

Sample Input 2

3
1 6 4

Sample Output 2

3

Explanation 2

botEnergy   height  delta
3           1       +2
5           6       -1
4           4       0
4

We can try lower values to assure that they won’t work.

Limbajul de programare folosit: java8

Cod:

//Problem: https://www.hackerrank.com/challenges/chief-hopper
//Java 8
import java.io.*;
import java.util.*;
import java.lang.Math;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner input = new Scanner(System.in);
        int N = input.nextInt();
        int[] buildings = new int[N];
        int minEnergy = 0;
        
        //Builds an array of the input
        for(int i = 0; i < N; i++)
        {
            buildings[i] = input.nextInt();
        }
        
        //Goes through the input in reverse calculating the min energy required based on ending with 0 energy
        for(int i = buildings.length-1; i >= 0; i--)
        {
            int buildingHeight = buildings[i];
            
            if(buildingHeight > minEnergy)
            {
                minEnergy += (int) Math.ceil((buildingHeight - minEnergy) / 2.0);
            }
            else if(buildingHeight < minEnergy) 
            {
                minEnergy = (int) Math.ceil((buildingHeight + minEnergy) / 2.0);
            }
            
            //Nothing occurs in the == case so we simply don't check for it
        }
        
        System.out.println(minEnergy);
    }
}

Scor obtinut: 1.0

Submission ID: 464603324

Link challenge: https://www.hackerrank.com/challenges/chief-hopper/problem

Chief Hopper