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(in) to stack2(out) if any **/publicclassQueueUseStack {privateD...
40. 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. Both pop and top methods should return the value...
with self.assertRaises(Exception): queue.dequeue() def test_error_when_dequeue_from_empty_queue(self): queue = QueueTwoStacks() queue.enqueue(1) queue.enqueue(2) actual = queue.dequeue() expected = 1 self.assertEqual(actual, expected) actual = queue.dequeue() expected = 2 self.assertEqual...
As the title described, you should only use two stacks to implement a queue’s actions. The queue should support push(element), pop() and top() 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. Challenge...
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...
To handle this, we can grow stacks from two extreme corners of the array. In other words, the first stack grows from the0'thindex, and the second stack grows from the(n-1)'thindex, wherenis the array size. Both stacks can grow towards each other with no fixed capacity. Now overflow...
last = node } // incrementing queue size this.size++ } Dequeue Method Pseudocode. Create a new method called dequeue. if the Queue is empty return null. declare a new variable called node and initialize with first property. if there is more than one element in the Queue then update the...
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The next data structure will help you get around the reallocation problem you saw with list. Using collections.deque to Create a Python Stack The collections module contains deque, which is useful for creating Python stacks. deque is pronounced “deck” and stands for “double-ended queue.” Yo...
The Pop function checks whether the stack is empty, if not then it prints the topmost item and deletes it from the stack. The Third function will simply print all the elements of the stack if exist. If not, then it will say stack is Empty. ...