python数据结构——链表、栈、队列

一、思维梳理：

 二、双向循环链表：

class Node:
    def __init__(self,data):
        self.data = data
        self.next = None
        self.prev = None

class DoubleLink:
    def __init__(self):
        self.size = 0
        self.head = None

    def is_empty(self):
        return self.size == 0

    def add_end(self,data):
        node = Node(data)
        if self.is_empty():
          self.head = node
          node.next = node
          node.prev = node
        else:
            q = self.head.prev
            node.prev = q
            node.next = self.head
            q.next = node
            self.head.prev = node
        self.size += 1

    def del_end(self):
        if self.is_empty():
            return
        else:
            if self.size == 1:
                self.head = None
            else:
                q = self.head.prev
                self.head.prev = q.prev
                q.prev.next = self.head
            self.size -= 1

    def show(self):
        if self.is_empty():
            return
        else:
            q = self.head
            while q.next != self.head:
                print(q.data,end=" ")
                q = q.next
            print(q.data,end=" ")
            print()

if __name__ == '__main__':
    doubleLink = DoubleLink()

    doubleLink.add_end(10)
    doubleLink.add_end(20)
    doubleLink.add_end(30)
    doubleLink.add_end(40)
    doubleLink.add_end(50)

    doubleLink.show()

    doubleLink.del_end()
    doubleLink.show()

 结果展示：

10 20 30 40 50 
10 20 30 40 

三、顺序栈：

class Stack:
    def __init__(self,capacity):
        self.capacity = capacity
        self.size = 0
        self.data = [None]*capacity

    def is_empty(self):
        return self.size == 0

    def is_full(self):
        return self.size == self.capacity

    def push(self,data):
        if self.is_full():
            return
        self.data[self.size] = data
        self.size += 1

    def pop(self):
        if self.is_empty():
            return
        self.size -= 1

    def top(self):
        if self.is_empty():
            return
        return self.data[self.size-1]

    def get_size(self):
        return self.size

    def show(self):
        for i in range(self.size-1,-1,-1):
            print(self.data[i],end=" ")
        print()

if __name__ == '__main__':
    stack = Stack(100)

    stack.push(10)
    stack.push(20)
    stack.push(30)
    stack.push(40)

    stack.show()

    stack.pop()
    stack.show()

结果展示：

40 30 20 10 
30 20 10 

四、链式栈：

class Node:
    def __init__(self,data):
        self.data = data
        self.next = None

class Stack:
    def __init__(self):
        self.size = 0
        self.top = None

    def is_empty(self):
        return self.size == 0

    def push(self,data):
        node = Node(data)
        node.next = self.top
        self.top = node
        self.size += 1

    def pop(self):
        if self.is_empty():
            return
        else:
            self.top = self.top.next
            self.size -= 1

    def get_top(self):
        if self.is_empty():
            return
        return self.top.data

    def get_size(self):
        return self.size

    def show(self):
        if self.is_empty():
            return
        q = self.top
        while q:
            print(q.data,end=" ")
            q = q.next
        print()

if __name__ == '__main__':
    stack = Stack()

    stack.push(10)
    stack.push(20)
    stack.push(30)
    stack.push(40)
    stack.push(50)
    stack.push(60)

    stack.show()

    stack.pop()
    stack.show()

    print(stack.get_top())

    print(stack.get_size())

结果展示：

60 50 40 30 20 10 
50 40 30 20 10 
50
5