Implementations of a few sorting algorithms and there worst case performance written in python.

algorithms.py

#!/usr/bin/env python
import random

#Merge Sort Worst Case: O(n*Log(n))
def merge(left, right):
    result = []
    i ,j = 0, 0
    while i < len(left) and j < len(right):
        if left[i] <= right[j]:
            result.append(left[i])
            i += 1
        else:
            result.append(right[j])
            j += 1
    result += left[i:]
    result += right[j:]
    return result

def mergeSort(list):
    if len(list) < 2:
        return list
    middle = len(list) / 2
    left = mergesort(list[:middle])
    right = mergesort(list[middle:])
    return merge(left, right)

#Bubble Sort Worst Case: O(n^2)
def bubbleSort(list):
  length = len(list)
	for i in xrange(0,length-1):
		for j in xrange(0,length-1):
			if list[j+1] < list[j]:
				temp = list[j]
				list[j] = list[j+1]
				list[j+1] = temp
				
	return list

#Insertion Sort Worst Case: O(n^2)
def insertionSort(list):
	for i in xrange(1, len(list)):
		j = i
		while j > 0 and list[j] < list[j-1]:
			list[j-1], list[j] = list[j], list[j-1]
			j -= 1
	return list

#Selection Sort Worst Case: O(n^2)
def selectionSort(list):
	for i in xrange(0, len(list)):
		min_index = i
		for j in xrange(i, len(list)):
			if list[j] < list[min_index]:
				min_index = j
		list[i], list[min_index] = list[min_index], list[i]
	return list
#Quick Sort Worst Case: O(n^2) (extremely Rare)
def quickSort(list):
	if len(list) <= 1:
		return list
		
	pivot = list.pop()
	less = []
	gr8t = []
	
	for i in list:
		if i <= pivot:
			less.append(i)
		else:
			gr8t.append(i)
			
	return quickSort(less) + [pivot] + quickSort(gr8t)
        
#Main	
def main():
	list = random.sample(xrange(100), 50)
	print "Unsorted"
	print list
    
	print "Merge Sorted"
	print mergeSort(list)
	
	print "Bubble Sorted"
	print bubbleSort(list)
	
	print "Insertion Sorted"
	print insertionSort(list)
	
	print "Selection Sorted"
	print selectionSort(list)
	
	print "Quick Sorted"
	print quickSort(list)

main()