添加225. 用队列实现栈JavaScript版本

problems/0225.用队列实现栈.md

@@ -357,8 +357,115 @@ class MyStack:
 
 Go：
 
+javaScript: 
 
+使用数组（push, shift）模拟队列
 
+```js
+
+// 使用两个队列实现
+/**
+ * Initialize your data structure here.
+ */
+var MyStack = function() {
+    this.queue1 = [];
+    this.queue2 = [];
+};
+
+/**
+ * Push element x onto stack. 
+ * @param {number} x
+ * @return {void}
+ */
+MyStack.prototype.push = function(x) {
+    this.queue1.push(x);
+};
+
+/**
+ * Removes the element on top of the stack and returns that element.
+ * @return {number}
+ */
+MyStack.prototype.pop = function() {
+    // 减少两个队列交换的次数， 只有当queue1为空时，交换两个队列
+    if(!this.queue1.length) {
+        [this.queue1, this.queue2] = [this.queue2, this.queue1];
+    }
+    while(this.queue1.length > 1) {
+        this.queue2.push(this.queue1.shift());
+    }
+    return this.queue1.shift();
+};
+
+/**
+ * Get the top element.
+ * @return {number}
+ */
+MyStack.prototype.top = function() {
+    const x = this.pop();
+    this.queue1.push(x);
+    return x;
+};
+
+/**
+ * Returns whether the stack is empty.
+ * @return {boolean}
+ */
+MyStack.prototype.empty = function() {
+    return !this.queue1.length && !this.queue2.length;
+};
+
+```
+
+```js
+
+// 使用一个队列实现
+/**
+ * Initialize your data structure here.
+ */
+var MyStack = function() {
+    this.queue = [];
+};
+
+/**
+ * Push element x onto stack. 
+ * @param {number} x
+ * @return {void}
+ */
+MyStack.prototype.push = function(x) {
+    this.queue.push(x);
+};
+
+/**
+ * Removes the element on top of the stack and returns that element.
+ * @return {number}
+ */
+MyStack.prototype.pop = function() {
+    let size = this.queue.length;
+    while(size-- > 1) {
+        this.queue.push(this.queue.shift());
+    }
+    return this.queue.shift();
+};
+
+/**
+ * Get the top element.
+ * @return {number}
+ */
+MyStack.prototype.top = function() {
+    const x = this.pop();
+    this.queue.push(x);
+    return x;
+};
+
+/**
+ * Returns whether the stack is empty.
+ * @return {boolean}
+ */
+MyStack.prototype.empty = function() {
+    return !this.queue.length;
+};
+
+```
 
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 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)