JS链表实现栈和队列

1. 栈

top指针记录栈顶元素，插入和删除都是对top操作

function Node(val) {
    this.val = val;
    this.next = null;
}
function Stack() {
    this.top = null;
    this.length = 0;
}
/* 入栈 */
Stack.prototype.push = function (node) {
    if (!this.top) {
        this.top = node;
        this.length++;
    } else {
        node.next = this.top;
        this.top = node;
        this.length++;
    }
}
/* 出栈 */
Stack.prototype.pop = function () {
    let res = this.top || undefined;
    // 删除栈顶
    if (this.top) {
        this.top = this.top.next;
        this.length--;
    }
    return res;
}

let stack = new Stack();
stack.push(new Node(1));
stack.push(new Node(2));
stack.pop();
console.log(JSON.stringify(stack, null, '   '));
stack.pop();
console.log(JSON.stringify(stack, null, '   '));

2. 队列

/* 队列 */
function Node(val) {
    this.val = val;
    this.next = null;
}
function Queue() {
    this.front = null;
    this.tail = null;
    this.length = 0;
}
/* 插入 */
Queue.prototype.insert = function (node) {
    if (!this.front) {
        this.front = this.tail = node;
    } else {
        /* 新插入元素放到尾部 */
        this.tail.next = node;
        this.tail = node;
    }
    this.length++;
}
/* 弹出 */
Queue.prototype.pop = function () {
    if (!this.length)
        return -1;
    /* 从头部删除 */
    let res = this.front;
    this.front = this.front.next;
    this.length--;
    /* 删除完毕将尾部删除 */
    if (!this.length)
        this.tail = null;
    return res;
}

let queue = new Queue();
queue.insert(new Node(1));
queue.insert(new Node(2));
queue.pop();
console.log(JSON.stringify(queue, null, '   '));
queue.pop();
console.log(JSON.stringify(queue, null, '   '));