剑指Offer09:用两个栈实现队列(Golang/Python/C#)

package main

type CQueue struct {
	inStack, outStack []int
}

func Constructor() CQueue {
	return CQueue{}
}

func (this *CQueue) AppendTail(value int) {
	this.inStack = append(this.inStack, value)
}

func (this *CQueue) in2out() {
	for len(this.inStack) > 0 {
		this.outStack = append(this.outStack, this.inStack[len(this.inStack)-1])
		this.inStack = this.inStack[:len(this.inStack)-1]
	}
}

func (this *CQueue) DeleteHead() int {
	if len(this.outStack) == 0 {
		if len(this.inStack) == 0 {
			return -1
		}
		this.in2out()
	}
	value := this.outStack[len(this.outStack)-1]
	this.outStack = this.outStack[:len(this.outStack)-1]
	return value
}

class CQueue:

    def __init__(self):
        self.stack = []
        self.cache = []

    def appendTail(self, value: int) -> None:
        self.stack.append(value)

    def deleteHead(self) -> int:
        if self.cache: return self.cache.pop()
        if not self.stack: return -1
        while self.stack:
            self.cache.append(self.stack.pop())
        return self.cache.pop()

public class CQueue
{
    private Stack<int> stack;
    private Stack<int> cache;
    public CQueue()
    {
        stack = new Stack<int>();
        cache = new Stack<int>();
    }

    public void AppendTail(int value)
    {
        stack.Push(value);
    }

    public int DeleteHead()
    {
        if (cache.Count != 0) {
            return cache.Pop();
        }
        if (stack.Count == 0) {
            return -1;
        }
        while(stack.Count != 0) {
            cache.Push(stack.Pop());
        }
        return cache.Pop();
    }
}