用栈实现队列 (opens new window)

• 难度：Easy
• 标签：

刷题思路

• [x] 用数组实现队列(简单但不可取)
• [x] 用两个栈实现队列

方法 1 用数组实现队列

方法 2 用两个栈实现队列

/**
 * Initialize your data structure here.
 */
var MyQueue = function() {
    this.mStack = []
    this.stack = []
};

/**
 * Push element x to the back of queue. 
 * @param {number} x
 * @return {void}
 */
MyQueue.prototype.push = function(x) {
    while (this.stack.length !== 0) this.mStack.push(this.stack.pop())
    this.mStack.push(x)
    while (this.mStack.length !== 0) this.stack.push(this.mStack.pop())
};

/**
 * Removes the element from in front of queue and returns that element.
 * @return {number}
 */
MyQueue.prototype.pop = function() {
    return this.stack.pop()
};

/**
 * Get the front element.
 * @return {number}
 */
MyQueue.prototype.peek = function() {
    const ele = this.stack.pop()
    this.stack.push(ele)
    return ele
};

/**
 * Returns whether the queue is empty.
 * @return {boolean}
 */
MyQueue.prototype.empty = function() {
    return this.peek() === undefined
};

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