常见的排序算法实现，常见排序算法实现,import rando
import random # for generating random numbersimport time # for timing each sort function with time.clock()DEBUG = False # set True to check results of each sortN = 1000 # number of elements in listlist1 = [] # list of integer elementsfor i in range(0, N): list1.append(random.randint(0, N-1))#print list1 # testdef print_timing(func): def wrapper(*arg): t1 = time.clock() res = func(*arg) t2 = time.clock() print '%s took %0.3fms' % (func.func_name, (t2-t1)*1000.0) return res return wrapper# declare the @ decorator just above each sort function, invokes print_timing()@print_timingdef adaptive_merge_sort(list2): """adaptive merge sort, built into Python since version 2.3""" list2.sort()@print_timingdef bubble_sort(list2): swap_test = False for i in range(0, len(list2) - 1): for j in range(0, len(list2) - i - 1): if list2[j] > list2[j + 1]: list2[j], list2[j + 1] = list2[j + 1], list2[j] # swap swap_test = True if swap_test == False: break# selection sort@print_timingdef selection_sort(list2): for i in range(0, len (list2)): min = i for j in range(i + 1, len(list2)): if list2[j] < list2[min]: min = j list2[i], list2[min] = list2[min], list2[i] # swap# insertion sort@print_timingdef insertion_sort(list2): for i in range(1, len(list2)): save = list2[i] j = i while j > 0 and list2[j - 1] > save: list2[j] = list2[j - 1] j -= 1 list2[j] = save# quick sort@print_timingdef quick_sort(list2): quick_sort_r(list2, 0, len(list2) - 1)# quick_sort_r, recursive (used by quick_sort)def quick_sort_r(list2 , first, last): if last > first: pivot = partition(list2, first, last) quick_sort_r(list2, first, pivot - 1) quick_sort_r(list2, pivot + 1, last)# partition (used by quick_sort_r)def partition(list2, first, last): sred = (first + last)/2 if list2[first] > list2 [sred]: list2[first], list2[sred] = list2[sred], list2[first] # swap if list2[first] > list2 [last]: list2[first], list2[last] = list2[last], list2[first] # swap if list2[sred] > list2[last]: list2[sred], list2[last] = list2[last], list2[sred] # swap list2 [sred], list2 [first] = list2[first], list2[sred] # swap pivot = first i = first + 1 j = last while True: while i <= last and list2[i] <= list2[pivot]: i += 1 while j >= first and list2[j] > list2[pivot]: j -= 1 if i >= j: break else: list2[i], list2[j] = list2[j], list2[i] # swap list2[j], list2[pivot] = list2[pivot], list2[j] # swap return j# heap sort@print_timingdef heap_sort(list2): first = 0 last = len(list2) - 1 create_heap(list2, first, last) for i in range(last, first, -1): list2[i], list2[first] = list2[first], list2[i] # swap establish_heap_property (list2, first, i - 1)# create heap (used by heap_sort)def create_heap(list2, first, last): i = last/2 while i >= first: establish_heap_property(list2, i, last) i -= 1# establish heap property (used by create_heap)def establish_heap_property(list2, first, last): while 2 * first + 1 <= last: k = 2 * first + 1 if k < last and list2[k] < list2[k + 1]: k += 1 if list2[first] >= list2[k]: break list2[first], list2[k] = list2[k], list2[first] # swap first = k# merge sort@print_timingdef merge_sort(list2): merge_sort_r(list2, 0, len(list2) -1)# merge sort recursive (used by merge_sort)def merge_sort_r(list2, first, last): if first < last: sred = (first + last)/2 merge_sort_r(list2, first, sred) merge_sort_r(list2, sred + 1, last) merge(list2, first, last, sred)# merge (used by merge_sort_r)def merge(list2, first, last, sred): helper_list = [] i = first j = sred + 1 while i <= sred and j <= last: if list2 [i] <= list2 [j]: helper_list.append(list2[i]) i += 1 else: helper_list.append(list2 [j]) j += 1 while i <= sred: helper_list.append(list2[i]) i +=1 while j <= last: helper_list.append(list2[j]) j += 1 for k in range(0, last - first + 1): list2[first + k] = helper_list [k]# test sorted list by printing the first 10 elementsdef print10(list2): for k in range(10): print list2[k], print# run test if script is executedif __name__ == "__main__" : print "timing 7 sorting algorithms with a list of 1000 integers:" # make a true copy of list1 each time list2 = list(list1) adaptive_merge_sort(list2) if DEBUG: print10(list2) list2 = list(list1) bubble_sort(list2) if DEBUG: print10(list2) list2 = list(list1) heap_sort(list2) if DEBUG: print10(list2) list2 = list(list1) insertion_sort(list2) if DEBUG: print10(list2) list2 = list(list1) merge_sort(list2) if DEBUG: print10(list2) list2 = list(list1) quick_sort(list2) if DEBUG: print10(list2) list2 = list(list1) selection_sort(list2) if DEBUG: print10(list2) # final test list2 = list(list1) if DEBUG: print "final test: ", print10(list2) #raw_input( "Press Enter to continue..." )#该片段来自于http://byrx.net
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