一、單鏈表反轉

#!/usr/bin/python
#遞迴實現單鏈表反轉

class ListNode(object):
  def __init__(self,x):
    self.val=x
    self.next=None


def recurse(head,newhead):  #遞迴，head為原連結串列的頭結點，newhead為反轉後連結串列的頭結點
  if head is None:
    return
  if head.next is None:
    newhead=head
  else :
    newhead=recurse(head.next,newhead)
    head.next.next=head
    head.next=None
  return newhead



if __name__ == '__main__':
    head=ListNode(1)       #測試程式碼
    p1=ListNode(2)       # 建立連結串列1->2->3->4->None
    p2=ListNode(3)
    p3=ListNode(4)
    head.next=p1
    p1.next=p2
    p2.next=p3
    newhead=None
    p=recurse(head,newhead)    #輸出連結串列4->3->2->1->None
    while p:
      print(p.val)
      p=p.next
 

二、字串倒序

#寫一個函式, 輸入一個字串, 返回倒序排列的結果
#1).利用字串本身的翻轉

str = 'abcdef'
# def string_reverse(string):
#     return string[::-1]
#
# if __name__ =="__main__":
#     print(str)
#     print(string_reverse(str))

#2).把字串變成列表，用列表的reverse函式
# def string_reverse2(string):
#     new_str = list(string)
#     new_str.reverse()
#     return ''.join(new_str)
# if __name__ =="__main__":
#     print(str)
#     print(string_reverse2(str))


#3).新建一個列表，從後往前取
# def string_reverse3(string):
#     new_str = []
#     for i in range(1,len(string)+1):
#         new_str.append(string[-i])
#
#     return ''.join(new_str)
#
# if __name__ =="__main__":
#     print(str)
#     print(string_reverse3(str))

#4).利用雙向列表deque中的extendleft函式
# from collections import deque
#
# def string_reverse4(string):
#     d = deque()
#     d.extendleft(string)
#     return ''.join(d)
#
# if __name__ =="__main__":
#     print(str)
#     print(string_reverse4(str))

#5).遞迴
# def string_reverse5(string):
#     if len(string)<=1:
#         return string
#     else:
#         return string_reverse5(string[1:])+string[0]
#
# if __name__ =="__main__":
#     print(str)
#     print(string_reverse5(str))
 

三、list去重

# 1.按升序合併如下兩個list, 並去除重複的元素
list1 = [2, 3, 8, 4, 9, 5, 6]

list2 = [5, 6, 10, 17, 11, 2]

list3 = list1 + list2

sort_list = sorted(list(set(list3)))

print(sort_list)

四、排序

1.氣泡排序

時間複雜度：O(n2)

#coding:utf-8
#!/usr/bin/python

def bubble_sort(list):
    for i in range(len(list)-1):
        for j in range(len(list)-i-1):
            if list[j]>list[j+1]:
                list[j],list[j+1] = list[j+1],list[j]
    return list

if __name__ == '__main__':
    list = [2,3,5,19,3,5,6,7]
    print(bubble_sort(list))
 

2.快速排序

時間複雜度：O(nlogn)

版本一：

#!/usr/bin/python3
#-*- coding:utf-8 -*-

def sub_sort(lists,low,high):
    key = lists[low]
    while low < high:
        while low < high and lists[high] >= key:
            high -= 1
            lists[low] = lists[high]
            print("===========")
            print("low=")
            print(low)
            print("high=")
            print(high)
            print(lists)
        while low < high and lists[high] < key:

            low += 1
            lists[high] = lists[low]
            print("===========")
            print("low=")
            print(low)
            print("high=")
            print(high)
            print(lists)
    lists[low] = key
    return low

def quick_sort(array, low, high):
    if low < high:
        key_index = sub_sort(array,low,high)
        #遞迴進行排序
        quick_sort(array, low, key_index)
        quick_sort(array, key_index+1, high)


if __name__ == "__main__":
    lists = [3, 5, 4, 2, 1, 6]
    print(lists)
    quick_sort(lists, 0, 5)

版本二(自己寫)：

# coding:utf-8
# /usr/bin/python
import time
import sys

def calc_time(func):
    def wrapper(*args, **kwargs):
        start_time = time.time()
        result = func(*args, **kwargs)
        end_time = time.time()
        print(start_time)
        print(end_time)
        print("%s waster time is %s"%(func.__name__, end_time - start_time))
        return result
    return wrapper



def quick_sort(data, left, right):
    if left < right:
        mid = partition(data, left, right)
        quick_sort(data, left, mid - 1)
        quick_sort(data, mid + 1, right)


def partition(data, left, right):
    tmp = data[left]
    while left < right:
        while left < right and data[right] >= tmp:
            right -= 1
        data[left] = data[right]

        while left < right and data[left] <= tmp:
            left += 1
        data[right] = data[left]
    data[left] = tmp
    return left

@calc_time
def quick_sort_x(data):
    return quick_sort(data, 0, len(data) - 1)


if __name__ == '__main__':
    sys.setrecursionlimit(10000)
    lists = list(range(1000))
    #print(lists)
    quick_sort_x(lists)
    #print(lists)