quicksort in python
def partition(arr, low, high):
i = (low-1)
pivot = arr[high]
for j in range(low, high):
if arr[j] <= pivot:
i = i+1
arr[i], arr[j] = arr[j], arr[i]
arr[i+1], arr[high] = arr[high], arr[i+1]
return (i+1)
def quickSort(arr, low, high):
if len(arr) == 1:
return arr
if low < high:
pi = partition(arr, low, high)
quickSort(arr, low, pi-1)
quickSort(arr, pi+1, high)
arr = [10, 7, 8, 9, 1, 5]
n = len(arr)
quickSort(arr, 0, n-1)
print("Sorted array is:")
for i in range(n):
print("%d" % arr[i]),
def partition(array, begin, end):
pivot_idx = begin
for i in xrange(begin+1, end+1):
if array[i] <= array[begin]:
pivot_idx += 1
array[i], array[pivot_idx] = array[pivot_idx], array[i]
array[pivot_idx], array[begin] = array[begin], array[pivot_idx]
return pivot_idx
def quick_sort_recursion(array, begin, end):
if begin >= end:
return
pivot_idx = partition(array, begin, end)
quick_sort_recursion(array, begin, pivot_idx-1)
quick_sort_recursion(array, pivot_idx+1, end)
def quick_sort(array, begin=0, end=None):
if end is None:
end = len(array) - 1
return quick_sort_recursion(array, begin, end)
# 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 len(arr) == 1:
return arr
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:")
for i in range(n):
print("%d" % arr[i]),
# This code is contributed by Mohit Kumra
#This code in improved by https://github.com/anushkrishnav
# 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:")
for i in range(n):
print ("%d" %arr[i]),
# This code is contributed by Mohit Kumra
