[DS+Algo] 004 栈、队列及其代码实现

1. Stack

• FILO (FirstInLastOut) 的链表结构
• 在程序编译环境上使用较多
• 常用操作
  • push
  • pop
  • peek
  • is_empty
  • size
• Python 代码示例

class Stack(object):
    def __init__(self):
        self.items = []

    def is_empty(self):
        return self.items == []

    def push(self, item):
        self.items.append(item)

    def pop(self):
        return self.items.pop()

    def peek(self):
        return self.items[-1]

    def size(self):
        return len(self.items)

if __name__ == "__main__":
    stack = Stack()
    print(stack.is_empty())

    stack.push('a')
    stack.push('b')
    stack.push('c')
    print(stack.size())
    print(stack.peek())
    print(stack.pop())
    print(stack.pop())
    print(stack.pop())

2. Queue

2.1 queue

• FIFO (FirstInFastOut) 的链表结构
• 处理消息的时候使用比较多
  • 生产者消费者模型
• 常用操作
  • enqueue
  • dequeue
  • is_empty
  • size
• Python 代码示例

class Queue(object):
    def __init__(self):
        self.items = []

    def is_empty(self):
        return self.items == []

    def enqueue(self, item):
        self.items.insert(0, item)

    def dequeue(self):
        return self.items.pop()

    def size(self):
        return len(self.items)

if __name__ == "__main__":
    queue = Queue()
    print(queue.is_empty())

    queue.enqueue('a')
    queue.enqueue('b')
    queue.enqueue('c')
    print(queue.size())
    print(queue.dequeue())
    print(queue.dequeue())
    print(queue.dequeue())

2.2 dequeue

• dequeue = double-ended-queue
• 队头队尾均可入队、出队
• 常用操作
  • add_front
  • add_rear
  • remove_front
  • remove_rear
  • is_empty
  • size
• Python 代码示例

class Deque(object):
    def __init__(self):
        self.items = []

    def is_empty(self):
        return self.items == []

    def add_front(self, item):
        self.items.insert(0, item)

    def add_rear(self, item):
        self.items.append(item)

    def remove_front(self):
        return self.items.pop(0)

    def remove_rear(self):
        return self.items.pop()

    def size(self):
        return len(self.items)

if __name__ == "__main__":
    deque = Deque()

    deque.add_front(2)
    deque.add_front(1)
    deque.add_rear(3)
    deque.add_rear(4)
    print(">>> size:", deque.size())

    print(deque.remove_front())
    print(deque.remove_front())
    print(deque.remove_rear())
    print(deque.remove_rear())
    print(">>> size:", deque.size())