implement_stack_using_queues.md

🔥 Implement Stack using Queues 🔥 || 3 Solutions || Simple Fast and Easy || with Explanation

Solution - 1 Single Queue

import'dart:collection'; classMyStack { // Runtime: 467 ms, faster than 50.00% of Dart online submissions for Implement Stack using Queues.// Memory Usage: 143 MB, less than 75.00% of Dart online submissions for Implement Stack using Queues.Queue<int> queue =Queue(); MyStack() { this.queue; } voidpush(int x) { queue.add(x); for (int i =0; i < queue.length -1; i++) { queue.add(queue.removeFirst()); } } intpop() { return queue.removeFirst(); } inttop() { return queue.first; } boolempty() { return queue.isEmpty; } }

Solution - 2 Double Queue

import'dart:collection'; classMyStack { // Runtime: 469 ms, faster than 50.00% of Dart online submissions for Implement Stack using Queues.// Memory Usage: 143 MB, less than 50.00% of Dart online submissions for Implement Stack using Queues.Queue<int> queueOne =Queue(); Queue<int> queueTwo =Queue(); MyStack() { this.queueOne; this.queueTwo; } voidpush(int x) { if (queueOne.isEmpty && queueTwo.isEmpty) { queueOne.add(x); } elseif (queueOne.isEmpty) { queueOne.add(x); while (queueTwo.isNotEmpty) { queueOne.add(queueTwo.removeFirst()); } } elseif (queueTwo.isEmpty) { queueTwo.add(x); while (queueOne.isNotEmpty) { queueTwo.add(queueOne.removeFirst()); } } } intpop() { if (queueOne.isNotEmpty) { return queueOne.removeFirst(); } elseif (queueTwo.isNotEmpty) return queueTwo.removeFirst(); elsereturn-1; } inttop() { if (queueOne.isNotEmpty) { return queueOne.first; } elseif (queueTwo.isNotEmpty) return queueTwo.first; elsereturn-1; } boolempty() { return queueTwo.isEmpty && queueOne.isEmpty; } }

Bonus Solution - Go 😈

typeMyStackstruct { queue []int } /** Initialize your data structure here. */funcConstructor() MyStack { returnMyStack{ []int{} } } /** Push element x onto stack. */func (this*MyStack) Push(xint) { this.queue=append(this.queue[:0], append([]int{x}, this.queue[0:]...)...) // prepend } /** Removes the element on top of the stack and returns that element. */func (this*MyStack) Pop() int { temp:=this.queue[0] this.queue=this.queue[1:] returntemp } /** Get the top element. */func (this*MyStack) Top() int { returnthis.queue[0] } /** Returns whether the stack is empty. */func (this*MyStack) Empty() bool { returnlen(this.queue) ==0 }