feat: azl397985856#232

README.en.md

@@ -97,14 +97,14 @@ The data structures mainly includes:
 - [0020.Valid Parentheses](./problems/20.validParentheses.md)
 - [0026.remove-duplicates-from-sorted-array](./problems/26.remove-duplicates-from-sorted-array.md)
 - [0088.merge-sorted-array](./problems/88.merge-sorted-array.md)
-- [0104.maximum-depth-of-binary-tree](./problems/104.maximum-depth-of-binary-tree.md) 🆕
+- [0104.maximum-depth-of-binary-tree](./problems/104.maximum-depth-of-binary-tree.md)
 - [0121.best-time-to-buy-and-sell-stock](./problems/121.best-time-to-buy-and-sell-stock.md)
 - [0122.best-time-to-buy-and-sell-stock-ii](./problems/122.best-time-to-buy-and-sell-stock-ii.md)
 - [0125.valid-palindrome](./problems/125.valid-palindrome.md) 🆕
 - [0136.single-number](./problems/136.single-number.md)
 - [0155.min-stack](./problems/155.min-stack.md) 🆕
 - [0167.two-sum-ii-input-array-is-sorted](./problems/167.two-sum-ii-input-array-is-sorted.md)
-- [0172.factorial-trailing-zeroes](./problems/172.factorial-trailing-zeroes.md) 🆕
+- [0172.factorial-trailing-zeroes](./problems/172.factorial-trailing-zeroes.md)
 - [0169.majority-element](./problems/169.majority-element.md)
 - [0190.reverse-bits](./problems/190.reverse-bits.md)
 - [0191.number-of-1-bits](./problems/191.number-of-1-bits.md)
@@ -113,6 +113,7 @@ The data structures mainly includes:
 - [0206.reverse-linked-list](./problems/206.reverse-linked-list.md)
 - [0219.contains-duplicate-ii](./problems/219.contains-duplicate-ii.md)
 - [0226.invert-binary-tree](./problems/226.invert-binary-tree.md)
+- [0232.implement-queue-using-stacks](./problems/232.implement-queue-using-stacks.md) 🆕
 - [0263.ugly-number](./problems/263.ugly-number.md)
 - [0283.move-zeroes](./problems/283.move-zeroes.md)
 - [0342.power-of-four](./problems/342.power-of-four.md)

README.md

@@ -97,14 +97,14 @@ leetcode 题解，记录自己的 leetcode 解题之路。
 - [0020.Valid Parentheses](./problems/20.validParentheses.md)
 - [0026.remove-duplicates-from-sorted-array](./problems/26.remove-duplicates-from-sorted-array.md)
 - [0088.merge-sorted-array](./problems/88.merge-sorted-array.md)
-- [0104.maximum-depth-of-binary-tree](./problems/104.maximum-depth-of-binary-tree.md) 🆕
+- [0104.maximum-depth-of-binary-tree](./problems/104.maximum-depth-of-binary-tree.md)
 - [0121.best-time-to-buy-and-sell-stock](./problems/121.best-time-to-buy-and-sell-stock.md)
 - [0122.best-time-to-buy-and-sell-stock-ii](./problems/122.best-time-to-buy-and-sell-stock-ii.md)
 - [0125.valid-palindrome](./problems/125.valid-palindrome.md) 🆕
 - [0136.single-number](./problems/136.single-number.md)
 - [0155.min-stack](./problems/155.min-stack.md) 🆕
 - [0167.two-sum-ii-input-array-is-sorted](./problems/167.two-sum-ii-input-array-is-sorted.md)
-- [0172.factorial-trailing-zeroes](./problems/172.factorial-trailing-zeroes.md) 🆕
+- [0172.factorial-trailing-zeroes](./problems/172.factorial-trailing-zeroes.md)
 - [0169.majority-element](./problems/169.majority-element.md)
 - [0190.reverse-bits](./problems/190.reverse-bits.md)
 - [0191.number-of-1-bits](./problems/191.number-of-1-bits.md)
@@ -113,6 +113,7 @@ leetcode 题解，记录自己的 leetcode 解题之路。
 - [0206.reverse-linked-list](./problems/206.reverse-linked-list.md)
 - [0219.contains-duplicate-ii](./problems/219.contains-duplicate-ii.md)
 - [0226.invert-binary-tree](./problems/226.invert-binary-tree.md)
+- [0232.implement-queue-using-stacks](./problems/232.implement-queue-using-stacks.md) 🆕
 - [0263.ugly-number](./problems/263.ugly-number.md)
 - [0283.move-zeroes](./problems/283.move-zeroes.md)
 - [0342.power-of-four](./problems/342.power-of-four.md)

assets/drawio/232.implement-queue-using-stacks.drawio

@@ -0,0 +1 @@
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problems/232.implement-queue-using-stacks.md

@@ -0,0 +1,138 @@
+## 题目地址
+
+https://leetcode.com/problems/implement-queue-using-stacks/description/
+
+## 题目描述
+
+```
+Implement the following operations of a queue using stacks.
+
+push(x) -- Push element x to the back of queue.
+pop() -- Removes the element from in front of queue.
+peek() -- Get the front element.
+empty() -- Return whether the queue is empty.
+Example:
+
+MyQueue queue = new MyQueue();
+
+queue.push(1);
+queue.push(2);  
+queue.peek();  // returns 1
+queue.pop();   // returns 1
+queue.empty(); // returns false
+Notes:
+
+You must use only standard operations of a stack -- which means only push to top, peek/pop from top, size, and is empty operations are valid.
+Depending on your language, stack may not be supported natively. You may simulate a stack by using a list or deque (double-ended queue), as long as you use only standard operations of a stack.
+You may assume that all operations are valid (for example, no pop or peek operations will be called on an empty queue).
+```
+
+## 思路
+
+这道题目是让我们用栈来模拟实现队列。 我们直到栈和队列都是一种受限的数据结构。
+栈的特点是只能在一端进行所有操作，队列的特点是只能在一端入队，另一端出队。
+
+在这里我们可以借助另外一个栈，也就是说用两个栈来实现队列的效果。这种做法的时间复杂度和空间复杂度都是O(n)。
+
+由于栈只能操作一端，因此我们peek或者pop的时候也只去操作顶部元素，要达到目的
+我们需要在push的时候将队头的元素放到栈顶即可。
+
+因此我们只需要在push的时候，用一下辅助栈即可。
+具体做法是先将栈清空并依次放到另一个辅助栈中，辅助栈中的元素再次放回栈中，最后将新的元素push进去即可。
+
+比如我们现在栈中已经是1，2，3，4了。 我们现在要push一个5.
+
+push之前是这样的：
+
+![232.implement-queue-using-stacks.drawio](../assets/problems/232.implement-queue-using-stacks-1.jpg)
+
+然后我们将栈中的元素转移到辅助栈：
+
+![232.implement-queue-using-stacks.drawio](../assets/problems/232.implement-queue-using-stacks-2.jpg)
+
+最后将新的元素添加到栈顶。
+
+![232.implement-queue-using-stacks.drawio](../assets/problems/232.implement-queue-using-stacks-3.jpg)
+
+
+整个过程是这样的：
+
+![232.implement-queue-using-stacks.drawio](../assets/problems/232.implement-queue-using-stacks-4.jpg)
+## 关键点解析
+
+- 在push的时候利用辅助栈(双栈)
+
+## 代码
+
+```js
+
+
+/*
+ * @lc app=leetcode id=232 lang=javascript
+ *
+ * [232] Implement Queue using Stacks
+ */
+/**
+ * Initialize your data structure here.
+ */
+var MyQueue = function() {
+  // tag: queue stack array
+  this.stack = [];
+  this.helperStack = [];
+};
+
+/**
+ * Push element x to the back of queue.
+ * @param {number} x
+ * @return {void}
+ */
+MyQueue.prototype.push = function(x) {
+  let cur = null;
+  while ((cur = this.stack.pop())) {
+    this.helperStack.push(cur);
+  }
+  this.helperStack.push(x);
+
+  while ((cur = this.helperStack.pop())) {
+    this.stack.push(cur);
+  }
+};
+
+/**
+ * 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() {
+  return this.stack[this.stack.length - 1];
+};
+
+/**
+ * Returns whether the queue is empty.
+ * @return {boolean}
+ */
+MyQueue.prototype.empty = function() {
+  return this.stack.length === 0;
+};
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * var obj = new MyQueue()
+ * obj.push(x)
+ * var param_2 = obj.pop()
+ * var param_3 = obj.peek()
+ * var param_4 = obj.empty()
+ */
+```
+
+## 扩展
+ - 类似的题目有用队列实现栈，思路是完全一样的，大家有兴趣可以试一下。
+ - 栈混洗也是借助另外一个栈来完成的，从这点来看，两者有相似之处。
+