stack1(in): is the only stack to store new elements when adding a new element into the queue stack2(out): is the only stack to pop old element out of the queue. when stack2 is empty, we move all data from stack1
Implement Queue by Two Stacks Implement the following operations of a queue using stacks. push(x) -- Push element x to the back of queue. pop() -- Removes the element from in front of queue. peek() -- Get the front element. empty() -- Return whether the queue is empty. 1classMy...
class QueueTwoStacks(object): # Implement the enqueue and dequeue methods def enqueue(self, item): pass def dequeue(self): pass # Tests class Test(unittest.TestCase): def test_basic_queue_operations(self): queue = QueueTwoStacks() queue.enqueue(1) queue.enqueue(2) queue.enqueue(3) actual...
http://www.lintcode.com/en/problem/implement-queue-by-two-stacks/ 【题目解析】 用两个Stack来实现一个Queue,可以考虑到push()时,几乎与Queue中的offer()一样,都是加在末尾,区别是当Stack pop()时,取出的是最近加入(newest)的元素,而Queue用poll()则是将最老(oldest)的元素取出。使用2个Stack,可以将s...
1. 232 Implement Queue using Stacks 1.1 问题描写叙述 使用栈模拟实现队列。模拟实现例如以下操作: push(x). 将元素x放入队尾。 pop(). 移除队首元素。 peek(). 获取队首元素。 empty(). 推断队列是否为空。 注意:仅仅能使用栈的标准操作,push,pop,size和empty函数。
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AQueueimplements First In First Out while aStackis First In Last Out. It is possible to implement a queue using two stacks. When an item is to be inserted into the queue, we always push it to the first stack, and when we pop one element from the queue, we implement as popping it ...
The queue should supportpush(element),pop()andtop()where pop is pop the first(a.k.a front) element in the queue. Both pop and top methods should return the value of first element. 来源:http://www.lintcode.com/en/problem/implement-queue-by-two-stacks/ ...
Implement Queue by Two Stacks As the title described, you should only use two stacks to implement a queue's actions. The queue should supportpush(element),pop()andtop()where pop is pop the first(a.k.a front) element in the queue. ...
正如标题所述,你需要使用两个栈来实现队列的一些操作。 队列应支持push(element),pop() 和 top(),其中pop是弹出队列中的第一个(最前面的)元素。 pop和top方法都应该返回第一个元素的值。 样例 比如 push(1), pop(), push(2), push(3), top(), pop(),你应该返回1,2和2 ...