【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());
    }