python選擇排序簡單實現

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#!/usr/bin/env python3# -*- coding: UTF-8 -*-# Date:2018-5-27# Author:AreLIN#選擇排序:每次只取一個最大或最小值的索引import randoma = []count_swap = 0count_iter = 0#隨機數列表for _ in range(20): a.append(random.randrange(1,101))print("my first list:\n{}".format(a))for i in range(len(a)): maxindex = i for j in range(i+1,len(a)): count_iter += 1 if a[maxindex] < a[j]: maxindex = j if i != maxindex: a[maxindex],a[i] = a[i],a[maxindex] count_swap += 1print("My end list:\n{} {} {}".format(a,count_iter,count_swap))

#二元選擇排序：一次取兩個值（最大最小）的索引a = []count_swap = 0count_iter = 0#隨機數列表for _ in range(20):    a.append(random.randrange(1,101))print("my first list:\n{}".format(a))for i in range(len(a)//2):    maxindex = i    minindex = -i - 1    minorign = minindex    for j in range(i+1,len(a)-i):        count_iter += 1        if a[maxindex] < a[j]:            maxindex = j        if a[minindex] > a[-j-1]:            minindex = -j - 1    print("{} {} ".format(maxindex,minindex),end=‘|‘)    if i != maxindex:        a[maxindex],a[i] = a[i],a[maxindex]        count_swap += 1        if (i == minindex) or (i == (len(a) + minindex)):            minindex = maxindex    if minorign != minindex:        a[minindex],a[minorign] = a[minorign],a[minindex]        count_swap += 1print("The end list is:\n{},count_swap:{},count_iter:{}".format(a,count_swap,count_iter))

二元選擇排序迴圈的次數更低，效率更高

python選擇排序簡單實現