Python: Quick sort
Python Search and Sorting: Exercise-9 with Solution
Write a Python program to sort a list of elements using the quick sort algorithm.
Note : According to Wikipedia "Quicksort is a comparison sort, meaning that it can sort items of any type for which a "less-than" relation (formally, a total order) is defined. In efficient implementations it is not a stable sort, meaning that the relative order of equal sort items is not preserved. Quicksort can operate in-place on an array, requiring small additional amounts of memory to perform the sorting."
Sample Solution:
Python Code:
def quickSort(data_list):
quickSortHlp(data_list,0,len(data_list)-1)
def quickSortHlp(data_list,first,last):
if first < last:
splitpoint = partition(data_list,first,last)
quickSortHlp(data_list,first,splitpoint-1)
quickSortHlp(data_list,splitpoint+1,last)
def partition(data_list,first,last):
pivotvalue = data_list[first]
leftmark = first+1
rightmark = last
done = False
while not done:
while leftmark <= rightmark and data_list[leftmark] <= pivotvalue:
leftmark = leftmark + 1
while data_list[rightmark] >= pivotvalue and rightmark >= leftmark:
rightmark = rightmark -1
if rightmark < leftmark:
done = True
else:
temp = data_list[leftmark]
data_list[leftmark] = data_list[rightmark]
data_list[rightmark] = temp
temp = data_list[first]
data_list[first] = data_list[rightmark]
data_list[rightmark] = temp
return rightmark
data_list = [54,26,93,17,77,31,44,55,20]
quickSort(data_list)
print(data_list)
Sample Output:
[17, 20, 26, 31, 44, 54, 55, 77, 93]
Flowchart:
Python Code Editor :
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