chosen, usually the first element. All elements smaller than the pivot are placed to the left of the pivot. This creates 2 partitions, elements greater than the pivot and element
Quick Sort is another sorting
- A pivot element is chosen, usually the first element.
- All elements smaller than the pivot are placed to the left of the pivot. This creates 2 partitions, elements greater than the pivot and elements less than the pivot.
- The 2 partitions are sorted using Quick Sort.
Sample code in python3:
def quick_sort(arr):
def quick_sort_r(arr, start, end):
if end - start < 2:
# single element base case
return
# choose a pivot
pivot = start # you may choose other elements
store = pivot+1 # index to store less than elements
# for all elements after the pivot
for i in range(pivot+1, end):
if arr[i] < arr[pivot]:
# if element is less than pivot
arr[i], arr[store] = arr[store], arr[i] # swap
store += 1 # increment store index
# swap pivot with last element in less than partition
arr[pivot], arr[store-1] = arr[store-1], arr[pivot]
pivot = store-1 # new pivot index
# Recursive Calls
quick_sort_r(arr, start, pivot) # sort less than partition
quick_sort_r(arr, pivot+1, end) # sort greater than partition
return
quick_sort_r(arr, 0, len(arr))
ANSWER THE FOLLOWING QUESTIONS.
1. Does the choice of the pivot affect the running time of quick sort? Why or why not? If you can draw some figures to explain, it would be much better.
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