【算法总结】【队列均LinkedList】栈和队列、双端队列的使用及案例

1、栈

初始化：Stack<E> stack = new Stack<>();

出栈：stack.pop() 或 stack.remove(stack.size() - 1)

入栈：stack.push(2) 或 stack.add(1)

栈顶：stack.peek()

2、队列

初始化：Queue<E> queue = new LinkedList<>();

入队：queue.offer(2) 或 queue.add(3)

出队：queue.poll() 或 queue.remove()

查看队头元素：queue.peek()

3、双端队列

初始化：

//Deque<Integer> deque = new ArrayDeque<>();
Deque<Integer> deque1 = new LinkedList<>();

入队：

deque1.addFirst(1);
deque1.addLast(2);
deque1.offerFirst(3);
deque1.offerLast(4);

出队：

deque1.removeFirst()

deque1.removeLast()

deque1.pollFirst()

deque1.pollLast()

查看队头元素：

deque1.peekFirst()

deque1.peekLast()

4、测试

public static void main(String[] args) {

        //System.out.println(isValid("([])"));

        //testQueue();

        testStack();

    }

    public static void testDeque() {

        //双端队列

        Deque<Integer> deque = new ArrayDeque<>();

        Deque<Integer> deque1 = new LinkedList<>();

        //入队

        deque1.addFirst(1);

        deque1.addLast(2);

        deque1.offerFirst(3);

        deque1.offerLast(4);

        System.out.println(deque1.peekFirst());

        System.out.println(deque1.peekLast());

        //出队

        System.out.println(deque1.removeFirst());

        System.out.println(deque1.removeLast());

        System.out.println(deque1.pollFirst());

        System.out.println(deque1.pollLast());

    }

    public static void testQueue() {

        Queue<Integer> queue = new LinkedList<>();

        queue.offer(1);

        queue.offer(2);

        queue.add(3);

        System.out.println(queue.peek());

        System.out.println(queue.poll());

        System.out.println(queue.peek());

        System.out.println(queue.remove());

        System.out.println(queue.peek());

    }

    public static void testStack() {

        Stack<Integer> stack = new Stack<>();

        stack.add(1);

        stack.push(2);

        stack.push(3);

        System.out.println(stack.peek());

        System.out.println(stack.pop());

        System.out.println(stack.peek());

        System.out.println(stack.remove(stack.size() - 1));

        System.out.println(stack.peek());

    }