Stack・Queを自己実装

• 追加削除はどちらもO(N)

Stack(FIFO)

# Stack(FIFO)
class Stack:
    def __init__(self):
        self.items = []
    def is_empty(self):
        return len(self.items) == 0
    def push(self, item):
        self.items.append(item)
    def pop(self):
        return self.items.pop()
    def peek(self):
        last = len(self.items)-1
        return self.items[last]
    def size(self):
        return len(self.items)

Queue(FILO)

class Queue:
    def __init__(self):
        self.items = []
    def is_empty(self):
        return len(self.items) == 0
    def enqueue(self, item):
        self.items.insert(0, item)
    def dequeue(self):
        return self.items.pop()
    def size(self):
        return len(self.items)