Quick Sort In Python

# Python program for implementation of Quicksort Sort

# This function takes last element as pivot, places

# the pivot element at its correct position in sorted

# array, and places all smaller (smaller than pivot)

# to left of pivot and all greater elements to right

# of pivot

def partition(arr, low, high):

    i = (low - 1)  # index of smaller element

    pivot = arr[high]  # pivot

    for j in range(low, high):

        # If current element is smaller than or

        # equal to pivot

        if arr[j] <= pivot:

            # increment index of smaller element

            i = i + 1

            arr[i], arr[j] = arr[j], arr[i]

    arr[i + 1], arr[high] = arr[high], arr[i + 1]

    return (i + 1)

# The main function that implements QuickSort

# arr[] --> Array to be sorted,

# low --> Starting index,

# high --> Ending index

# Function to do Quick sort

def quickSort(arr, low, high):

    if low < high:

        # pi is partitioning index, arr[p] is now

        # at right place

        pi = partition(arr, low, high)

        # Separately sort elements before

        # partition and after partition

        quickSort(arr, low, pi - 1)

        quickSort(arr, pi + 1, high)

    # Driver code to test above

arr = [10, 7, 8, 9, 1, 5]

n = len(arr)

quickSort(arr, 0, n - 1)

print("Sorted array is: {}".format(arr))

# This code is contributed by Mohit Kumra