【算法刷题day10】Leetcode:232.用栈实现队列、225. 用队列实现栈

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java的Deque

Leetcode 232.用栈实现队列

题目：232.用栈实现队列
解析：代码随想录解析

解题思路

一个栈负责进，一个栈负责出

代码

class MyQueue {Stack<Integer> stackIn;Stack<Integer> stackOut;public MyQueue() {stackIn = new Stack<>();stackOut = new Stack<>();}public void push(int x) {stackIn.push(x);}public int pop() {dumpStackIn();return stackOut.pop();}public int peek() {dumpStackIn();return stackOut.peek();}public boolean empty() {if (stackOut.isEmpty() && stackIn.isEmpty())return true;return false;}public void dumpStackIn(){if (!stackOut.isEmpty())return;while(!stackIn.isEmpty()){stackOut.push(stackIn.pop());}}
}/*** Your MyQueue object will be instantiated and called as such:* MyQueue obj = new MyQueue();* obj.push(x);* int param_2 = obj.pop();* int param_3 = obj.peek();* boolean param_4 = obj.empty();*/

总结

暂无

Leetcode 225. 用队列实现栈

题目：225. 用队列实现栈
解析：代码随想录解析

解题思路

每次使用一个辅助队列来存储后入元素，然后把队列元素插入辅助队列中，再对换索引。

代码

class MyStack {Queue<Integer> queue1;Queue<Integer> queue2;public MyStack() {queue1 = new LinkedList<>();queue2 = new LinkedList<>();}public void push(int x) {queue2.offer(x);while(!queue1.isEmpty()){queue2.offer(queue1.poll());}Queue<Integer> queueTmp = queue1;queue1 = queue2;queue2 = queueTmp;}public int pop() {return queue1.poll();}public int top() {return queue1.peek();}public boolean empty() {return queue1.isEmpty();}
}/*** Your MyStack object will be instantiated and called as such:* MyStack obj = new MyStack();* obj.push(x);* int param_2 = obj.pop();* int param_3 = obj.top();* boolean param_4 = obj.empty();*/

总结

暂无

stack、queue和deque对比