A: new

README.md

@@ -62,17 +62,23 @@ LeetCode Problems' Solutions
 
 | # | Title | Solution | Difficulty |
 | :-: | - | - | :-: |
+| <span id="1495">1495</span> | [Friendly Movies Streamed Last Month](https://leetcode.com/problems/friendly-movies-streamed-last-month) 🔒 | [MySQL](problems/friendly-movies-streamed-last-month) | Easy |
+| <span id="1494">1494</span> | [Parallel Courses II](https://leetcode.com/problems/parallel-courses-ii "并行课程 II") | [Go](problems/parallel-courses-ii) | Hard |
+| <span id="1493">1493</span> | [Longest Subarray of 1's After Deleting One Element](https://leetcode.com/problems/longest-subarray-of-1s-after-deleting-one-element "删掉一个元素以后全为 1 的最长子数组") | [Go](problems/longest-subarray-of-1s-after-deleting-one-element) | Medium |
+| <span id="1492">1492</span> | [The kth Factor of n](https://leetcode.com/problems/the-kth-factor-of-n "n 的第 k 个因子") | [Go](problems/the-kth-factor-of-n) | Medium |
+| <span id="1491">1491</span> | [Average Salary Excluding the Minimum and Maximum Salary](https://leetcode.com/problems/average-salary-excluding-the-minimum-and-maximum-salary "去掉最低工资和最高工资后的工资平均值") | [Go](problems/average-salary-excluding-the-minimum-and-maximum-salary) | Easy |
+| <span id="1490">1490</span> | [Clone N-ary Tree](https://leetcode.com/problems/clone-n-ary-tree "克隆 N 叉树") 🔒 | [Go](problems/clone-n-ary-tree) | Medium |
 | <span id="1489">1489</span> | [Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree](https://leetcode.com/problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree "找到最小生成树里的关键边和伪关键边") | [Go](problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree) | Hard |
 | <span id="1488">1488</span> | [Avoid Flood in The City](https://leetcode.com/problems/avoid-flood-in-the-city "避免洪水泛滥") | [Go](problems/avoid-flood-in-the-city) | Medium |
 | <span id="1487">1487</span> | [Making File Names Unique](https://leetcode.com/problems/making-file-names-unique "保证文件名唯一") | [Go](problems/making-file-names-unique) | Medium |
 | <span id="1486">1486</span> | [XOR Operation in an Array](https://leetcode.com/problems/xor-operation-in-an-array "数组异或操作") | [Go](problems/xor-operation-in-an-array) | Easy |
 | <span id="1485">1485</span> | [Clone Binary Tree With Random Pointer](https://leetcode.com/problems/clone-binary-tree-with-random-pointer "克隆含随机指针的二叉树") 🔒 | [Go](problems/clone-binary-tree-with-random-pointer) | Medium |
-| <span id="1484">1484</span> | [Group Sold Products By The Date](https://leetcode.com/problems/group-sold-products-by-the-date) 🔒 | [MySQL](problems/group-sold-products-by-the-date) | Easy |
+| <span id="1484">1484</span> | [Group Sold Products By The Date](https://leetcode.com/problems/group-sold-products-by-the-date "按日期分组销售产品") 🔒 | [MySQL](problems/group-sold-products-by-the-date) | Easy |
 | <span id="1483">1483</span> | [Kth Ancestor of a Tree Node](https://leetcode.com/problems/kth-ancestor-of-a-tree-node "树节点的第 K 个祖先") | [Go](problems/kth-ancestor-of-a-tree-node) | Hard |
 | <span id="1482">1482</span> | [Minimum Number of Days to Make m Bouquets](https://leetcode.com/problems/minimum-number-of-days-to-make-m-bouquets "制作 m 束花所需的最少天数") | [Go](problems/minimum-number-of-days-to-make-m-bouquets) | Medium |
 | <span id="1481">1481</span> | [Least Number of Unique Integers after K Removals](https://leetcode.com/problems/least-number-of-unique-integers-after-k-removals "不同整数的最少数目") | [Go](problems/least-number-of-unique-integers-after-k-removals) | Medium |
 | <span id="1480">1480</span> | [Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array "一维数组的动态和") | [Go](problems/running-sum-of-1d-array) | Easy |
-| <span id="1479">1479</span> | [Sales by Day of the Week](https://leetcode.com/problems/sales-by-day-of-the-week) 🔒 | [MySQL](problems/sales-by-day-of-the-week) | Hard |
+| <span id="1479">1479</span> | [Sales by Day of the Week](https://leetcode.com/problems/sales-by-day-of-the-week "周内每天的销售情况") 🔒 | [MySQL](problems/sales-by-day-of-the-week) | Hard |
 | <span id="1478">1478</span> | [Allocate Mailboxes](https://leetcode.com/problems/allocate-mailboxes "安排邮筒") | [Go](problems/allocate-mailboxes) | Hard |
 | <span id="1477">1477</span> | [Find Two Non-overlapping Sub-arrays Each With Target Sum](https://leetcode.com/problems/find-two-non-overlapping-sub-arrays-each-with-target-sum "找两个和为目标值且不重叠的子数组") | [Go](problems/find-two-non-overlapping-sub-arrays-each-with-target-sum) | Medium |
 | <span id="1476">1476</span> | [Subrectangle Queries](https://leetcode.com/problems/subrectangle-queries "子矩形查询") | [Go](problems/subrectangle-queries) | Medium |
@@ -82,7 +88,7 @@ LeetCode Problems' Solutions
 | <span id="1472">1472</span> | [Design Browser History](https://leetcode.com/problems/design-browser-history "设计浏览器历史记录") | [Go](problems/design-browser-history) | Medium |
 | <span id="1471">1471</span> | [The k Strongest Values in an Array](https://leetcode.com/problems/the-k-strongest-values-in-an-array "数组中的 k 个最强值") | [Go](problems/the-k-strongest-values-in-an-array) | Medium |
 | <span id="1470">1470</span> | [Shuffle the Array](https://leetcode.com/problems/shuffle-the-array "重新排列数组") | [Go](problems/shuffle-the-array) | Easy |
-| <span id="1469">1469</span> | [Find All The Lonely Nodes](https://leetcode.com/problems/find-all-the-lonely-nodes) 🔒 | [Go](problems/find-all-the-lonely-nodes) | Easy |
+| <span id="1469">1469</span> | [Find All The Lonely Nodes](https://leetcode.com/problems/find-all-the-lonely-nodes "寻找所有的独生节点") 🔒 | [Go](problems/find-all-the-lonely-nodes) | Easy |
 | <span id="1468">1468</span> | [Calculate Salaries](https://leetcode.com/problems/calculate-salaries "计算税后工资") 🔒 | [MySQL](problems/calculate-salaries) | Medium |
 | <span id="1467">1467</span> | [Probability of a Two Boxes Having The Same Number of Distinct Balls](https://leetcode.com/problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls "两个盒子中球的颜色数相同的概率") | [Go](problems/probability-of-a-two-boxes-having-the-same-number-of-distinct-balls) | Hard |
 | <span id="1466">1466</span> | [Reorder Routes to Make All Paths Lead to the City Zero](https://leetcode.com/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero "重新规划路线") | [Go](problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero) | Medium |
@@ -116,13 +122,13 @@ LeetCode Problems' Solutions
 | <span id="1438">1438</span> | [Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit](https://leetcode.com/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit "绝对差不超过限制的最长连续子数组") | [Go](problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit) | Medium |
 | <span id="1437">1437</span> | [Check If All 1's Are at Least Length K Places Away](https://leetcode.com/problems/check-if-all-1s-are-at-least-length-k-places-away "是否所有 1 都至少相隔 k 个元素") | [Go](problems/check-if-all-1s-are-at-least-length-k-places-away) | Medium |
 | <span id="1436">1436</span> | [Destination City](https://leetcode.com/problems/destination-city "旅行终点站") | [Go](problems/destination-city) | Easy |
-| <span id="1435">1435</span> | [Create a Session Bar Chart](https://leetcode.com/problems/create-a-session-bar-chart) 🔒 | [MySQL](problems/create-a-session-bar-chart) | Easy |
+| <span id="1435">1435</span> | [Create a Session Bar Chart](https://leetcode.com/problems/create-a-session-bar-chart "制作会话柱状图") 🔒 | [MySQL](problems/create-a-session-bar-chart) | Easy |
 | <span id="1434">1434</span> | [Number of Ways to Wear Different Hats to Each Other](https://leetcode.com/problems/number-of-ways-to-wear-different-hats-to-each-other "每个人戴不同帽子的方案数") | [Go](problems/number-of-ways-to-wear-different-hats-to-each-other) | Hard |
 | <span id="1433">1433</span> | [Check If a String Can Break Another String](https://leetcode.com/problems/check-if-a-string-can-break-another-string "检查一个字符串是否可以打破另一个字符串") | [Go](problems/check-if-a-string-can-break-another-string) | Medium |
 | <span id="1432">1432</span> | [Max Difference You Can Get From Changing an Integer](https://leetcode.com/problems/max-difference-you-can-get-from-changing-an-integer "改变一个整数能得到的最大差值") | [Go](problems/max-difference-you-can-get-from-changing-an-integer) | Medium |
 | <span id="1431">1431</span> | [Kids With the Greatest Number of Candies](https://leetcode.com/problems/kids-with-the-greatest-number-of-candies "拥有最多糖果的孩子") | [Go](problems/kids-with-the-greatest-number-of-candies) | Easy |
-| <span id="1430">1430</span> | [Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree](https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree) 🔒 | [Go](problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree) | Medium |
-| <span id="1429">1429</span> | [First Unique Number](https://leetcode.com/problems/first-unique-number) 🔒 | [Go](problems/first-unique-number) | Medium |
+| <span id="1430">1430</span> | [Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree](https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree "判断给定的序列是否是二叉树从根到叶的路径") 🔒 | [Go](problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree) | Medium |
+| <span id="1429">1429</span> | [First Unique Number](https://leetcode.com/problems/first-unique-number "第一个唯一数字") 🔒 | [Go](problems/first-unique-number) | Medium |
 | <span id="1428">1428</span> | [Leftmost Column with at Least a One](https://leetcode.com/problems/leftmost-column-with-at-least-a-one "至少有一个 1 的最左端列") 🔒 | [Go](problems/leftmost-column-with-at-least-a-one) | Medium |
 | <span id="1427">1427</span> | [Perform String Shifts](https://leetcode.com/problems/perform-string-shifts "字符串的左右移") 🔒 | [Go](problems/perform-string-shifts) | Easy |
 | <span id="1426">1426</span> | [Counting Elements](https://leetcode.com/problems/counting-elements "数元素") 🔒 | [Go](problems/counting-elements) | Easy |

problems/average-salary-excluding-the-minimum-and-maximum-salary/README.md

@@ -0,0 +1,69 @@
+<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    openset <openset.wang@gmail.com>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+[< Previous](../clone-n-ary-tree "Clone N-ary Tree")
+
+[Next >](../the-kth-factor-of-n "The kth Factor of n")
+
+## [1491. Average Salary Excluding the Minimum and Maximum Salary (Easy)](https://leetcode.com/problems/average-salary-excluding-the-minimum-and-maximum-salary "去掉最低工资和最高工资后的工资平均值")
+
+<p>Given an array of <strong>unique</strong> integers <code>salary</code>&nbsp;where <code>salary[i]</code> is the salary of the employee <code>i</code>.</p>
+
+<p>Return the average salary of employees excluding the minimum and maximum salary.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> salary = [4000,3000,1000,2000]
+<strong>Output:</strong> 2500.00000
+<strong>Explanation: </strong>Minimum salary and maximum salary are 1000 and 4000 respectively.
+Average salary excluding minimum and maximum salary is (2000+3000)/2= 2500
+</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> salary = [1000,2000,3000]
+<strong>Output:</strong> 2000.00000
+<strong>Explanation: </strong>Minimum salary and maximum salary are 1000 and 3000 respectively.
+Average salary excluding minimum and maximum salary is (2000)/1= 2000
+</pre>
+
+<p><strong>Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> salary = [6000,5000,4000,3000,2000,1000]
+<strong>Output:</strong> 3500.00000
+</pre>
+
+<p><strong>Example 4:</strong></p>
+
+<pre>
+<strong>Input:</strong> salary = [8000,9000,2000,3000,6000,1000]
+<strong>Output:</strong> 4750.00000
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>3 &lt;= salary.length &lt;= 100</code></li>
+	<li><code>10^3&nbsp;&lt;= salary[i] &lt;= 10^6</code></li>
+	<li><code>salary[i]</code> is unique.</li>
+	<li>Answers within <code>10^-5</code> of the actual value will be accepted as correct.</li>
+</ul>
+
+### Related Topics
+  [[Sort](../../tag/sort/README.md)]
+  [[Array](../../tag/array/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Get the total sum and subtract the minimum and maximum value in the array.  Finally divide the result by n - 2.
+</details>

problems/buddy-strings/README.md

@@ -54,21 +54,20 @@
 <strong>Input: </strong>A = <span id="example-input-5-1">&quot;&quot;</span>, B = <span id="example-input-5-2">&quot;aa&quot;</span>
 <strong>Output: </strong><span id="example-output-5">false</span>
 </pre>
+</div>
+</div>
+</div>
+</div>
+</div>
 
 <p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
 
-<p><strong><span>Note:</span></strong></p>
-
-<ol>
+<ul>
 	<li><code>0 &lt;= A.length &lt;= 20000</code></li>
 	<li><code>0 &lt;= B.length &lt;= 20000</code></li>
 	<li><code>A</code> and&nbsp;<code>B</code> consist only of lowercase letters.</li>
-</ol>
-</div>
-</div>
-</div>
-</div>
-</div>
+</ul>
 
 ### Related Topics
   [[String](../../tag/string/README.md)]

problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/README.md

@@ -9,7 +9,7 @@
 
 [Next >](../kids-with-the-greatest-number-of-candies "Kids With the Greatest Number of Candies")
 
-## [1430. Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree (Medium)](https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree "")
+## [1430. Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree (Medium)](https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree "判断给定的序列是否是二叉树从根到叶的路径")
 
 
 

problems/climbing-stairs/README.md

@@ -15,8 +15,6 @@
 
 <p>Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?</p>
 
-<p><strong>Note:</strong> Given <em>n</em> will be a positive integer.</p>
-
 <p><strong>Example 1:</strong></p>
 
 <pre>
@@ -38,6 +36,13 @@
 3. 2 steps + 1 step
 </pre>
 
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= n &lt;= 45</code></li>
+</ul>
+
 ### Related Topics
   [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
 

problems/clone-n-ary-tree/README.md

@@ -0,0 +1,31 @@
+<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    openset <openset.wang@gmail.com>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+[< Previous](../find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree "Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree")
+
+[Next >](../average-salary-excluding-the-minimum-and-maximum-salary "Average Salary Excluding the Minimum and Maximum Salary")
+
+## [1490. Clone N-ary Tree (Medium)](https://leetcode.com/problems/clone-n-ary-tree "克隆 N 叉树")
+
+
+
+### Related Topics
+  [[Tree](../../tag/tree/README.md)]
+  [[Depth-first Search](../../tag/depth-first-search/README.md)]
+  [[Breadth-first Search](../../tag/breadth-first-search/README.md)]
+  [[Hash Table](../../tag/hash-table/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Traverse the tree, keep a hashtable with you and create a clone node for each node in the tree.
+</details>
+
+<details>
+<summary>Hint 2</summary>
+Start traversing the original tree again and connect each child pointer in the cloned tree the same way as the original tree with the help of the hashtable.
+</details>

problems/create-a-session-bar-chart/README.md

@@ -9,6 +9,6 @@
 
 [Next >](../destination-city "Destination City")
 
-## [1435. Create a Session Bar Chart (Easy)](https://leetcode.com/problems/create-a-session-bar-chart "")
+## [1435. Create a Session Bar Chart (Easy)](https://leetcode.com/problems/create-a-session-bar-chart "制作会话柱状图")
 
 

problems/excel-sheet-column-number/README.md

@@ -46,6 +46,14 @@
 <strong>Input: </strong>&quot;ZY&quot;
 <strong>Output:</strong> 701
 </pre>
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= s.length &lt;= 7</code></li>
+	<li><code>s</code> consists only of uppercase English letters.</li>
+	<li><code>s</code> is between &quot;A&quot; and &quot;FXSHRXW&quot;.</li>
+</ul>
 
 ### Related Topics
   [[Math](../../tag/math/README.md)]

problems/find-all-the-lonely-nodes/README.md

@@ -9,7 +9,7 @@
 
 [Next >](../shuffle-the-array "Shuffle the Array")
 
-## [1469. Find All The Lonely Nodes (Easy)](https://leetcode.com/problems/find-all-the-lonely-nodes "")
+## [1469. Find All The Lonely Nodes (Easy)](https://leetcode.com/problems/find-all-the-lonely-nodes "寻找所有的独生节点")
 
 
 

problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree/README.md

@@ -7,7 +7,7 @@
 
 [< Previous](../avoid-flood-in-the-city "Avoid Flood in The City")
 
-Next >
+[Next >](../clone-n-ary-tree "Clone N-ary Tree")
 
 ## [1489. Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree (Hard)](https://leetcode.com/problems/find-critical-and-pseudo-critical-edges-in-minimum-spanning-tree "找到最小生成树里的关键边和伪关键边")
 

problems/find-first-and-last-position-of-element-in-sorted-array/README.md

@@ -29,6 +29,16 @@
 <strong>Input:</strong> nums = [<code>5,7,7,8,8,10]</code>, target = 6
 <strong>Output:</strong> [-1,-1]</pre>
 
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>0 &lt;= nums.length &lt;= 10^5</code></li>
+	<li><code>-10^9&nbsp;&lt;= nums[i]&nbsp;&lt;= 10^9</code></li>
+	<li><code>nums</code> is a non decreasing array.</li>
+	<li><code>-10^9&nbsp;&lt;= target&nbsp;&lt;= 10^9</code></li>
+</ul>
+
 ### Related Topics
   [[Array](../../tag/array/README.md)]
   [[Binary Search](../../tag/binary-search/README.md)]

problems/first-unique-character-in-a-string/README.md

@@ -11,21 +11,21 @@
 
 ## [387. First Unique Character in a String (Easy)](https://leetcode.com/problems/first-unique-character-in-a-string "字符串中的第一个唯一字符")
 
-<p>Given a string, find the first non-repeating character in it and return it&#39;s index. If it doesn&#39;t exist, return -1.</p>
+<p>Given a string, find the first non-repeating character in it and return its index. If it doesn&#39;t exist, return -1.</p>
 
 <p><b>Examples:</b></p>
 
 <pre>
 s = &quot;leetcode&quot;
 return 0.
 
-s = &quot;loveleetcode&quot;,
+s = &quot;loveleetcode&quot;
 return 2.
 </pre>
 
 <p>&nbsp;</p>
 
-<p><b>Note:</b> You may assume the string contain only lowercase English letters.</p>
+<p><b>Note:</b> You may assume the string contains only lowercase English letters.</p>
 
 ### Related Topics
   [[Hash Table](../../tag/hash-table/README.md)]

problems/first-unique-number/README.md

@@ -9,7 +9,7 @@
 
 [Next >](../check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree "Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree")
 
-## [1429. First Unique Number (Medium)](https://leetcode.com/problems/first-unique-number "")
+## [1429. First Unique Number (Medium)](https://leetcode.com/problems/first-unique-number "第一个唯一数字")