标签:定义 顺序 instr 包装 from sea move deque ott
Python里面实现栈,就是把list包装成一个类,再添加一些方法作为栈的基本操作。
栈的实现:
class Stack(object): #初始化栈为空列表 def __init__(self): self.items = [] #self.__items = []可以把items变成私有属性 #判断栈是不是为空 def isEmpty(self): return len(self.items) ==0 #返回栈顶的元素 def peek(self): return self.items[-1] #返回栈的大小 def size(self): return len(self.items) #给栈加入新元素 def push(self,a): self.items.append(a) #删除栈顶的元素 def pop(self): return self.items.pop()
栈应用实例:十进制转化为二进制
def divideBy2(decNumber): remstack = Stack() #实例化一个栈,因为需要栈结构来存储数据,也是为了用到栈方法 while decNumber > 0: rem = decNumber%2 #除二倒取余法,最后反转拼接所有的余数 remstack.push(rem) #余数依次放到栈中储存起来 decNumber = decNumber // 2 binstring = ‘‘ while not remstack.is_empty(): binstring = binstring + str(remstack.pop()) #反序获取栈中的元素 return binstring print divideBy2(10)
队列实际上就是一个包装了的列表,从list[0]添加新元素,用pop()来获取,符合先进先出的规则。
class Queue: def __init__(self): self.items = [] def isEmpty(self): return self.items == [] def enqueue(self,item): #添加一个新元素item到队列的开头,这叫队尾 self.items.insert(0,item) def dequeue(self): #减去一个最后一个元素,这叫队首 return self.items.pop() def size(self): return len(self.items) def show(self): #自主添加的,好跟踪查看队列里有啥 return self.items
队列应用实例:热土豆
#就是一队人围着圈报数,从0开始,报到m就出局,看谁活最久。 from pythonds.basic.queue import Queue def HotPotato(namelist,num): simqueue = Queue() for name in namelist: simqueue.enqueue(name) #把先namelist添加到队列中去,ps:从下标是0的位置开始添加,整个插入完成以后序列就反过来了 while simqueue.size()>1: for i in range(num): # simqueue.enqueue(simqueue.dequeue()) #从列表的末尾减去什么就把什么添加到列表开头 simqueue.dequeue() #哪个排最后哪个就是热土豆,直接出局 return simqueue.dequeue() print HotPotato([‘lili‘,‘jiajia‘,‘dahu‘,‘wangba‘,‘daqing‘,‘tamato‘,‘potato‘,‘hehe‘],3)
基本链表的实现: #链表是环环相扣形成的序列结构,每一环首先定义self变量,其次要标记下一个变量。所以访问的时候只能按照顺序来。
class Node: def __init__(self,initdata): self.data = initdata self.next = None def getData(self): return self.data def getNext(self): return self.next def setData(self,newdata): self.data = newdata def setNext(self,newnext): self.next = newnext
无序链表:
class UnorderedList: def __init__(self): self.head = None #表示链表的头部不引用任何内容 def isEmpty(self): return self.head == None def add(self,item): #链表中有两个属性,一个是本身,一个是next, temp = Node(item) #这个设定了链表本身,也就是data,无序链表也是由node构成的 temp.setNext(self.head) #这个设定了next self.head = temp #把链表的data参数设定为无序列表的头----head def size(self): current = self.head count = 0 while current != None: count = count +1 current = current.getNext() return count def search(self,item): current = self.head found = False while current != None and not found: if current.getData() == item: found = True else: current = current.getNext() return found def remove(self,item): current = self.head previous=None found = False while not found: #找到要删除的item以后会跳出循环,此时current.getData()是要删除的项目 if current.getData()==item: found=True else: previous=current current=current.getNext() if previous ==None: #只有一种情况下,previous会是None,那就是要删除的是第一个,也就是想删除self.head self.head=current.getNext() else: previous.setNext(current.getNext()) # 本来的指向是previous.getData()--item(也就是previous.getNext(),还是current.getData())--current.getNext()
#要想删除item,那就把previous的指向改成current.getNext(),这样item就不能在原来的链表中瞎掺和了
有序链表:
class OrderedList: def __init__(self): self.head = None def isEmpty(self): #同无序列表 return self.head == None def show(self): current = self.head while current != None: print current.getData() current = current.getNext() def __iter__(self): current = self.head while current != None: yield current.getData() current = current.getNext() def size(self): #同无序列表 current = self.head count = 0 while current != None: count +=1 current =current.getNext() return count def search(self,item): #默认从小到大排列的链表 current = self.head found = False stop = False while current != None and not found and not stop: if current.getData() == item: found = True else: if current.getData() > item: stop = True else: current = current.getNext() return found def add(self,item): current = self.head previous = None stop = False while current != None and not stop: #有一个以上元素的情况 if current.getData() > item: stop = True else: previous = current current = current.getNext() #不用担心元素添加到最后的情况,因为链表中自带None封住了两头 temp = Node(item) if previous == None: #添加到链表头的情况 temp.setNext(self.head) self.head=temp else: temp.setNext(current) previous.setNext(temp) def remove(self, item): current = self.head previous = None found = False while not found: # 迭代每一项,得到要删除的那个,并且通过赋值前一个执行删除 if current.getData() == item: found = True else: previous = current current = current.getNext() if previous == None: # 如果删除的是第一项,那么把第二项变成第一项,否则给previous赋值 self.head = current.getNext() else: previous.setNext(current.getNext())
标签:定义 顺序 instr 包装 from sea move deque ott
原文地址:https://www.cnblogs.com/0-lingdu/p/9459525.html