LeetCode/go/implement-queue-using-stacks.go

package main

import (
	"slices"
)

type MyQueue struct {
	asQueue []int
	asStack []int
}

func NewQueue() MyQueue {
	return MyQueue{
		asQueue: make([]int, 0, 16),
		asStack: make([]int, 0, 16),
	}
}

// [XXX] Uncomment for LeetCode
// func Constructor() MyQueue {
// 	return NewQueue()
// }

func (this *MyQueue) Push(x int) {
	this.asStack = append(this.asStack, x)
}

func (this *MyQueue) ReverseIfNeeded() {
	if len(this.asQueue) > 0 {
		return
	}

	slices.Reverse(this.asStack)
	this.asQueue = this.asStack
	this.asStack = make([]int, 0, 16)
}

func (this *MyQueue) Pop() int {
	result := this.Peek()
	this.asQueue = this.asQueue[:len(this.asQueue)-1]
	return result
}

func (this *MyQueue) Peek() int {
	this.ReverseIfNeeded()

	return this.asQueue[len(this.asQueue)-1]
}

func (this *MyQueue) Empty() bool {
	return len(this.asStack) == 0 && len(this.asQueue) == 0
}

/**
 * Your MyQueue object will be instantiated and called as such:
 * obj := Constructor();
 * obj.Push(x);
 * param_2 := obj.Pop();
 * param_3 := obj.Peek();
 * param_4 := obj.Empty();
 */