Sorting: Bubble Sort HackerRank solution in Java | Programming Blog

Problem Description :

Given an array of integers, sort the array in ascending order using the Bubble Sort algorithm above. Once sorted, print the following three lines:

1. Array is sorted in numSwaps swaps., where numSwaps is the number of swaps that took place.
2. First Element: firstElement, where firstElement is the first element in the sorted array.
3. Last Element: lastElement, where lastElement is the last element in the sorted array.

See full description on HackerRank :

• Problem Description : Bubble Sort 
  

Input and Output :

Input :

a = [6, 4, 1]

Output :

1       [4,6,1]
2       [4,1,6]
3       [1,4,6]

Array is sorted in 3 swaps.  
First Element: 1  
Last Element: 6  

In this problem we already have bubble sort code. we have to simply print swap count, first element and last element after swap. So lets see solution.

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

class Result {

    public static void countSwaps(List<Integer> a) {
        int size = a.size();
        int totalSwap = 0;
        
        for (int i = 0; i < size; i++) {
            for (int j = 0; j < size - 1; j++) {

                // Swap adjacent elements if they are in decreasing order
                if (a.get(j) > a.get(j + 1)) {
                    int temp = a.get(j);
                    a.set(j, a.get(j + 1));
                    a.set(j+1, temp);
                    totalSwap++;
                }
            }
        }
        
        System.out.println("Array is sorted in " +totalSwap+ " swaps.");
        System.out.println("First Element: "+ a.get(0));
        System.out.println("Last Element: "+a.get(size-1));
    
    }
}

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

        int n = Integer.parseInt(bufferedReader.readLine().trim());

        String[] aTemp = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");

        List<Integer> a = new ArrayList<>();

        for (int i = 0; i < n; i++) {
            int aItem = Integer.parseInt(aTemp[i]);
            a.add(aItem);
        }

        Result.countSwaps(a);

        bufferedReader.close();
    }
}

Solution explanation :

• For count we have taken totalSwap variable and initialize with 0. In for loop we have to increment totalSwap variable after swapping values.
• After for loop we are printing totalSwap value. 
• For printing firstElement and lastElement from list we are using get() method of list.

 

Happy Coding. Happy Learning.

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