Bubble Sort

Write a method that takes in an array of ints and uses the Bubble Sort algorithm to sort the array 'in place' in ascending order. The method should return the same, in-place sorted array.

Note: Bubble sort is one of the most inefficient ways to sort a large array of integers. Nevertheless, it is an interview favorite. Bubble sort has a time complexity of O(n²). However, if the sample size is small, bubble sort provides a simple implementation of a classic sorting algorithm.

Examples:
bubbleSortArray({5,4,3}) -> {3,4,5}
bubbleSortArray({3}) -> {3}
bubbleSortArray({}) -> {}
{} -> [Empty] Array

Need a hand? Try out these hints, one at a time.

Quick hint to get things rolling

The key concept here is to compare all adjacent integers and swap them if the first number is greater than the number to its right in the array. Click on the red highlighted text in the description above to learn more about the Bubble Sort algorithm. Use two nested loops - the first being a reverse loop to iterate over the array. At the end of each iteration of the outer loop, the largest number should 'bubble' to the end of the array.

A more detailed explanation

Use a tail index to keep a track of the elements that have been bubbled(sorted) to the end. The outer loop should be a reverse loop that decrements the tail index after each iteration.
At the same time a nested for loop should iterate from the start to the tail bubbling each element to the end by swapping adjacent numbers if required. Use a temp variable to do the swap.

Final hint! You should be able to code the problem on viewing this.

1) Use an outer reverse for loop to iterate over the array, from arr.length - 1 to 0, keeping the index at the tail position.

2) Iterate the inner for loop over the array till the last unsorted element of the array - the tail position.

3) Swap if the next element is smaller than the current element arr[j] > arr[j+1].

public static int[] bubbleSortArray(int[] arr){
    


    
    return arr;
}

This Coding Interview Question is available with an answer in the following programming languages :

Java

Python

Bubble Sort

Quick hint to get things rolling

A more detailed explanation

Final hint! You should be able to code the problem on viewing this.

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This Coding Interview Question is available with an answer in the following programming languages :