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    HackerRank Solution: Jumping on the Clouds
    Published on: 18th July 2016

    This tutorial provides Java solution to "Jumping on the Clouds" challenge of HackerRank.

    Hackerrank Challenge Details


    Problem Statement:

    Emma is playing a new mobile game involving n clouds numbered from 0 to n - 1. A player initially starts out on cloud c0, and they must jump to cloud cn-1. In each step, she can jump from any cloud  to cloud  or cloud .

    There are two types of clouds, ordinary clouds and thunderclouds. The game ends if Emma jumps onto a thundercloud, but if she reaches the last cloud (i.e., cn-1), she wins the game!

    Jump

    Can you find the minimum number of jumps Emma must make to win the game? It is guaranteed that clouds c0 and cn-1 are ordinary-clouds and it is always possible to win the game.

    Input Format:

    The first line contains an integer, n (the total number of clouds). 
    The second line contains n space-separated binary integers describing clouds c0, c1, c2,..., cn-1.

    • If ci = 0, the ith cloud is an ordinary cloud.
    • If ci = 1, the ith cloud is a thundercloud.

    Output Format:

    Print the minimum number of jumps needed to win the game.

    Constraints:

    • 2 < n < 100
    • ci € {0, 1}
    • c0 = cn-1 = 0

    Sample Input 0:

    7
    0 0 1 0 0 1 0

    Sample Output 0:

    4

    Sample Input 1:

    6
    0 0 0 0 1 0

    Sample Output 1:

    3

    Explanation:

    Sample Case 0: 
    Because c2 and c5 in our input are both 1, Emma must avoid c2 and c5. Bearing this in mind, she can win the game with a minimum of 4 jumps:

    Sample Case 1: 
    The only thundercloud to avoid is c4. Emma can win the game in 3 jumps:

    Solution Details


    Java Implementation:

    package com.saintech.allprogtutorials.hackerrank.algos;
    
    import java.util.Scanner;
    
    /**
     * @author Sain Technology Solutions
     * 
     * Solution to Problem - https://www.hackerrank.com/challenges/jumping-on-the-clouds
     *
     */
    public class JumpingOnClouds {
    	
    	public static void main(String[] args) {
    		final Scanner in = new Scanner(System.in);
    		final int N = in.nextInt();
    		
    		// Put all the clouds in an array
    		final int[] clouds = new int[N];
    		for(int i = 0; i < N; i++) {
    			clouds[i] = in.nextInt();
    		}
    		
    		// Check if two steps can be taken by verifying cloud type at 
    		// second step. Otherwise check if one step can be taken by verifying 
    		// if we still have any more clouds. If none of these conditions are met,
    		// break out of infinite loop.
    		int noOfJumps = 0, i = 0;
    		while(true) {
    			if(i + 2 < N && clouds[i + 2] == 0) {
    				i += 2;
    			} else if(i + 1 < N) {
    				i++;
    			} else {
    				break;
    			}
    			noOfJumps++;
    		}
    		
    		System.out.println(noOfJumps);
    		
    		in.close();
    	}
    
    }
    

    Thank you for reading through the tutorial. In case of any feedback/questions/concerns, you can communicate same to us through your comments and we shall get back to you as soon as possible.

    Published on: 18th July 2016

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