Bubble sort with pointers using Python

Question

The code is not working for some test cases.

def bubbleSort(array):
    l = 0
    r = 1
    isSorted = False
    while not isSorted:
        isSorted = True
        while r <= len(array)-1:
            if array[r] < array[l]:
                swap(l, r, array)
                isSorted = False
            l += 1
            r += 1
    return array

def swap(i, j, array):
    array[i], array[j] = array[j], array[i]
    return

Can anyone help me resolve this issue??

Answer 1

You need to reinitialize r and l back to r = 1 and l = 0 inside while not isSorted: . Otherwise you would only be running the complete loop once since at the end of first iteration, r is already at len(array)

Answer 2

As far as your code is concerned you have to loop through all the elements every time isSorted is False . So, you have to initialize l = 0 and r = 1 every time when outer while loop executes.

---

There is no need to use two counter variables l & r , you can simply implement bubble sort as follows:

def bubbleSort(array):
    isSorted = False
    while not isSorted:
        isSorted = True
        for i in range(1, len(array)):
            if array[i] < array[i - 1]:
                swap(i, i - 1, array)
                isSorted = False
    return array

def swap(i, j, array):
    array[i], array[j] = array[j], array[i]
    return

And when you executes >>>print(bubbleSort([10, 2, 1, 3, 2, 6, 25]))

Output will be:

[1, 2, 2, 3, 6, 10, 25]