# 二分算法查找 时间复制度log(n)
def binary_search(list,item):
row = 0
high = len(list)-1
while row <= high:
mid = int((row + high) / 2)
print('mid'+str(mid))
guess = list[mid]
if item == guess:
return mid
if item < guess:
high = mid - 1
else:
row = mid + 1
return None
if __name__ == '__main__':
res = binary_search([1,3,4,5,7,9],4)
print(res)
# 选择排序 时间复杂度(O(n*n))
def find_smallest(arr):
smallest_idx = 0
smallest = arr[smallest_idx]
for i in range(len(arr)):
if arr[i] < smallest:
smallest_idx = i
smallest = arr[smallest_idx]
return smallest
def section_sort(arr):
new_arr = []
for i in range(len(arr)):
smallest = find_smallest(arr)
arr.remove(smallest)
new_arr.append(smallest)
print(new_arr)
if __name__ == '__main__':
section_sort([1,5,3,9])
# 快速排序 时间复杂度：O(nlog(n)) 分而治之
def quick_sort(arr):
if len(arr) < 2:
return arr
else:
pivot = arr[0]
less = [i for i in arr[1:] if i <= pivot]
greater = [i for i in arr[1:] if i> pivot]
return quick_sort(less) + [pivot] +quick_sort(greater)
if __name__ == '__main__':
new_arr = quick_sort([1,6,4,3])
print(new_arr)
#单向链表
#在python当中，所有的变量都是引用，也就是指针； a = 10,表示a 这个引用指向10这块内存；既然a 是引用，也可以去指向其他类型，如
# a= 'hello'
#在其他语言比如c语言当中，int a = 10;这个a 是10这个内存的别名；注意别名不是地址，比如我叫方煜逵，我的别名叫小方，但是我的地址是在员村XXX，你可以到员村XXX这个地址找到我，
#但是你到小方这个地址找到我，显然很扯！所以别名说的还是10这块内存；故这块内存是int类型，就无法在存其他了类型了；当然c语言引入指针类型int *b 来指向10这块内存
class SingleNode(object):
def __init__(self,item):
"""单链表的结点"""
# _item存放数据元素
self.item = item
# _next是下一个节点的标识
self.next = None
#单链表的实现
class SingleLinkList(object):
def __init__(self,head = None):
self.__head = head
def is_empty(self):
"""判断链表是否为空"""
return self.__head == None
def length(self):
"""链表长度"""
# cur初始时指向头节点
cur = self.__head
count = 0
# 尾节点指向None，当未到达尾部时
while cur != None:
count += 1
# 将cur后移一个节点
cur = cur.next
return count
def travel(self):
"""遍历链表"""
cur = self.__head
while cur != None:
print(cur.item,end=' ')
cur = cur.next
print('')
# 尾部添加元素
def append(self,item):
"""尾部添加元素"""
node = SingleNode(item)
# 先判断链表是否为空，若是空链表，则将_head指向新节点
if self.is_empty():
self.__head = node
# 若不为空，则找到尾部，将尾节点的next指向新节点
else:
cur = self.__head
while cur.next != None:
cur = cur.next
cur.next = node
#头部添加元素
def add(self,item):
"""头部添加元素"""
node = SingleNode(item)
node.next = self.__head
self.__head = node
def insert(self, pos, item):
if pos <= 0:
self.add(item)
elif pos >= self.length()-1:
self.append(item)
else:
node = SingleNode(item)
pre_cur = self.__head
cur_pos = 0
while cur_pos < pos-1:
pre_cur = pre_cur.next
cur_pos += 1
node.next = pre_cur.next
pre_cur.next = node
def search(self, item):
"""链表查找节点是否存在，并返回True或者False"""
cur = self.__head
while cur!= None:
if item == cur.item:
return True
else:
cur = cur.next
return False
def remove(self, item):
"""删除节点"""
cur = self.__head
pre = None
while cur!= None:
if item == cur.item:
# 如果第一个就是删除的节点
if cur == self.__head:
# 将头指针指向头节点的后一个节点
self.__head = cur.next
cur = self.__head
else:
pre.next = cur.next
pre = cur
cur = cur.next
else:
pre = cur
cur = cur.next
if __name__ == '__main__':
l = SingleLinkList()
l.append(1)
l.append(2)
l.append(3)
l.append(4)
l.append(5)
l.append(6)
l.travel()
#单向循环链表
class SingleNode(object):
def __init__(self,item):
"""单链表的结点"""
# _item存放数据元素
self.item = item
# _next是下一个节点的标识
self.next = None
#单链表的实现
class SingleSycLinkList(object):
def __init__(self,head = None):
if head:
self.__head = head
head.next = self.__head
else:
self.__head = None
def is_empty(self):
"""判断链表是否为空"""
return self.__head == None
def length(self):
"""链表长度"""
# cur初始时指向头节点
cur = self.__head
count = 1
# 尾节点指向None，当未到达尾部时
while cur.next != self.__head:
count += 1
# 将cur后移一个节点
cur = cur.next
return count
def travel(self):
"""遍历链表"""
if self.is_empty():
return
cur = self.__head
while cur.next != self.__head:
print(cur.item,end=' ')
cur = cur.next
print(cur.item, end=' ')
# 尾部添加元素
def append(self,item):
"""尾部添加元素"""
node = SingleNode(item)
# 先判断链表是否为空，若是空链表，则将_head指向新节点
if self.is_empty():
self.__head = node
node.next = self.__head
# 若不为空，则找到尾部，将尾节点的next指向新节点
else:
cur = self.__head
while cur.next != self.__head:
cur = cur.next
cur.next = node
node.next = self.__head
#头部添加元素
def add(self,item):
"""头部添加元素"""
node = SingleNode(item)
if self.is_empty():
self.append(item)
return
cur = self.__head
while cur.next != self.__head:
cur = cur.next
node.next = self.__head
cur.next = node
self.__head = node
def insert(self, pos, item):
if pos <= 0:
self.add(item)
elif pos >= self.length()-1:
self.append(item)
else:
node = SingleNode(item)
pre_cur = self.__head
cur_pos = 0
while cur_pos < pos-1:
pre_cur = pre_cur.next
cur_pos += 1
node.next = pre_cur.next
pre_cur.next = node
def search(self, item):
"""链表查找节点是否存在，并返回True或者False"""
if self.is_empty():
return False
cur = self.__head
while cur.next!= self.__head:
if item == cur.item:
return True
else:
cur = cur.next
if cur.item == item:
return True
return False
def remove(self, item):
"""删除节点"""
if self.is_empty():
return
cur = self.__head
pre = None
while cur.next!= self.__head:
if item == cur.item:
# 如果第一个就是删除的节点
if cur == self.__head:
# 将头指针指向头节点的后一个节点
real = self.__head
while real.next != self.__head:
real = real.next
real.next = cur.next
self.__head = cur.next
else:
pre.next = cur.next
pre = cur
cur = cur.next
else:
pre = cur
cur = cur.next
# real = self.__head
# while real.next != self.__head:
# real = real.next
if item == cur.item:
pre.next = self.__head
if __name__ == '__main__':
l = SingleSycLinkList()
l.append(1)
# l.append(2)
# l.append(3)
# #
# l.add(0)
# l.insert(1,2)
# l.append(4)
#
#
# l.append(5)
# l.append(6)
l.remove(1)
l.travel()
#双向链表
class Node(object):
def __init__(self,item):
self.item = item
self.pre = None
self.next = None
class DoubleLinkList(object):
def __init__(self,node = None):
self.__head = node
def is_empty(self):
"""链表是否为空"""
return self.__head == None
def length(self):
"""链表长度"""
cur = self.__head
count = 0
while cur != None:
cur = cur.next
count += 1
return count
def travel(self):
"""遍历链表"""
cur = self.__head
while cur!= None:
print(cur.item,end=' ')
cur = cur.next
print('')
def append(self,item):
"""链表尾部添加"""
node = Node(item)
if self.is_empty():
self.__head = node
else:
cur = self.__head
while cur.next != None:
cur = cur.next
cur.next = node
node.pre = cur
def add(self, item):
"""链表头部添加"""
node = Node(item)
if self.is_empty():
self.__head = node
else:
cur = self.__head
node.next = cur
cur.pre = node
self.__head = node
def insert(self,pos, item):
"""指定位置添加"""
node = Node(item)
if pos <=0:
self.add(item)
elif pos >= self.length()-1:
self.append(item)
else:
cur = self.__head
count = 0
while count < pos:
cur = cur.next
count += 1
cur.pre.next = node
cur.pre = node
node = cur.pre
node.next = cur
def search(self,item):
"""查找节点是否存在"""
cur = self.__head
while cur!=None:
if cur.item == item:
return True
cur = cur.next
return False
def remove(self,item):
"""删除节点"""
if self.is_empty():
return
else:
cur = self.__head
while cur != None:
if cur.item == item:
node_pre = cur.pre
node_next = cur.next
#当删除为首结点
if cur == self.__head:
self.__head = node_next
node_next.pre = None
# 当删除为尾结点
elif node_next == None:
cur.pre.next = None
else:
node_pre.next = node_next
node_next.pre = node_pre
cur = cur.next
if __name__ == '__main__':
dll = DoubleLinkList()
dll.append(2)
dll.append(3)
dll.append(4)
dll.append(5)
dll.add(1)
dll.insert(2,4)
dll.remove(1)
dll.travel()
