如何用栈结构实现队列结构:用两个栈拼队列结构
package com.harrison.class02; import java.util.Stack; public class Code07_TwoStacksImplementQueue { public static class TwoStacksToQueue{ public Stack<Integer> pushStack; public Stack<Integer> popStack; public TwoStacksToQueue() { pushStack=new Stack<Integer>(); popStack=new Stack<Integer>(); } public void pushToPop() { if(popStack.isEmpty()) { while(!pushStack.isEmpty()) { popStack.push(pushStack.pop()); } } } public void add(int pushInt) { pushStack.push(pushInt); pushToPop(); } public int poll() { if(pushStack.isEmpty() && popStack.isEmpty()) { throw new RuntimeException("队列空了!"); } pushToPop(); return popStack.pop(); } public int peek() { if(pushStack.isEmpty() && popStack.isEmpty()) { throw new RuntimeException("队列空了!"); } pushToPop(); return popStack.peek(); } } public static void main(String[] args) { TwoStacksToQueue test=new TwoStacksToQueue(); test.add(1); test.add(2); test.add(3); System.out.println(test.peek()); System.out.println(test.poll()); System.out.println(test.peek()); System.out.println(test.poll()); System.out.println(test.peek()); System.out.println(test.poll()); } }