Add: new

Author: openset

README.md

@@ -62,6 +62,11 @@ LeetCode Problems' Solutions
 
 | # | Title | Solution | Difficulty |
 | :-: | - | - | :-: |
+| <span id="1255">1255</span> | [Maximum Score Words Formed by Letters](https://leetcode.com/problems/maximum-score-words-formed-by-letters "得分最高的单词集合") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-score-words-formed-by-letters) | Hard |
+| <span id="1254">1254</span> | [Number of Closed Islands](https://leetcode.com/problems/number-of-closed-islands "统计封闭岛屿的数目") | [Go](https://github.com/openset/leetcode/tree/master/problems/number-of-closed-islands) | Medium |
+| <span id="1253">1253</span> | [Reconstruct a 2-Row Binary Matrix](https://leetcode.com/problems/reconstruct-a-2-row-binary-matrix "重构 2 行二进制矩阵") | [Go](https://github.com/openset/leetcode/tree/master/problems/reconstruct-a-2-row-binary-matrix) | Medium |
+| <span id="1252">1252</span> | [Cells with Odd Values in a Matrix](https://leetcode.com/problems/cells-with-odd-values-in-a-matrix "奇数值单元格的数目") | [Go](https://github.com/openset/leetcode/tree/master/problems/cells-with-odd-values-in-a-matrix) | Easy |
+| <span id="1251">1251</span> | [Average Selling Price](https://leetcode.com/problems/average-selling-price) 🔒 | [MySQL](https://github.com/openset/leetcode/tree/master/problems/average-selling-price) | Easy |
 | <span id="1250">1250</span> | [Check If It Is a Good Array](https://leetcode.com/problems/check-if-it-is-a-good-array "检查「好数组」") | [Go](https://github.com/openset/leetcode/tree/master/problems/check-if-it-is-a-good-array) | Hard |
 | <span id="1249">1249</span> | [Minimum Remove to Make Valid Parentheses](https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses "移除无效的括号") | [Go](https://github.com/openset/leetcode/tree/master/problems/minimum-remove-to-make-valid-parentheses) | Medium |
 | <span id="1248">1248</span> | [Count Number of Nice Subarrays](https://leetcode.com/problems/count-number-of-nice-subarrays "统计「优美子数组」") | [Go](https://github.com/openset/leetcode/tree/master/problems/count-number-of-nice-subarrays) | Medium |
@@ -70,7 +75,7 @@ LeetCode Problems' Solutions
 | <span id="1245">1245</span> | [Tree Diameter](https://leetcode.com/problems/tree-diameter "树的直径") 🔒 | [Go](https://github.com/openset/leetcode/tree/master/problems/tree-diameter) | Medium |
 | <span id="1244">1244</span> | [Design A Leaderboard](https://leetcode.com/problems/design-a-leaderboard "力扣排行榜") 🔒 | [Go](https://github.com/openset/leetcode/tree/master/problems/design-a-leaderboard) | Medium |
 | <span id="1243">1243</span> | [Array Transformation](https://leetcode.com/problems/array-transformation "数组变换") 🔒 | [Go](https://github.com/openset/leetcode/tree/master/problems/array-transformation) | Easy |
-| <span id="1242">1242</span> | [Web Crawler Multithreaded](https://leetcode.com/problems/web-crawler-multithreaded) 🔒 | [Go](https://github.com/openset/leetcode/tree/master/problems/web-crawler-multithreaded) | Medium |
+| <span id="1242">1242</span> | [Web Crawler Multithreaded](https://leetcode.com/problems/web-crawler-multithreaded "多线程网页爬虫") 🔒 | [Go](https://github.com/openset/leetcode/tree/master/problems/web-crawler-multithreaded) | Medium |
 | <span id="1241">1241</span> | [Number of Comments per Post](https://leetcode.com/problems/number-of-comments-per-post "每个帖子的评论数") 🔒 | [MySQL](https://github.com/openset/leetcode/tree/master/problems/number-of-comments-per-post) | Easy |
 | <span id="1240">1240</span> | [Tiling a Rectangle with the Fewest Squares](https://leetcode.com/problems/tiling-a-rectangle-with-the-fewest-squares "铺瓷砖") | [Go](https://github.com/openset/leetcode/tree/master/problems/tiling-a-rectangle-with-the-fewest-squares) | Hard |
 | <span id="1239">1239</span> | [Maximum Length of a Concatenated String with Unique Characters](https://leetcode.com/problems/maximum-length-of-a-concatenated-string-with-unique-characters "串联字符串的最大长度") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-length-of-a-concatenated-string-with-unique-characters) | Medium |
@@ -200,7 +205,7 @@ LeetCode Problems' Solutions
 | <span id="1115">1115</span> | [Print FooBar Alternately](https://leetcode.com/problems/print-foobar-alternately "交替打印FooBar") | [Go](https://github.com/openset/leetcode/tree/master/problems/print-foobar-alternately) | Medium |
 | <span id="1114">1114</span> | [Print in Order](https://leetcode.com/problems/print-in-order "按序打印") | [Go](https://github.com/openset/leetcode/tree/master/problems/print-in-order) | Easy |
 | <span id="1113">1113</span> | [Reported Posts](https://leetcode.com/problems/reported-posts) 🔒 | [MySQL](https://github.com/openset/leetcode/tree/master/problems/reported-posts) | Easy |
-| <span id="1112">1112</span> | [Highest Grade For Each Student](https://leetcode.com/problems/highest-grade-for-each-student) 🔒 | [MySQL](https://github.com/openset/leetcode/tree/master/problems/highest-grade-for-each-student) | Medium |
+| <span id="1112">1112</span> | [Highest Grade For Each Student](https://leetcode.com/problems/highest-grade-for-each-student "每位学生的最高成绩") 🔒 | [MySQL](https://github.com/openset/leetcode/tree/master/problems/highest-grade-for-each-student) | Medium |
 | <span id="1111">1111</span> | [Maximum Nesting Depth of Two Valid Parentheses Strings](https://leetcode.com/problems/maximum-nesting-depth-of-two-valid-parentheses-strings "有效括号的嵌套深度") | [Go](https://github.com/openset/leetcode/tree/master/problems/maximum-nesting-depth-of-two-valid-parentheses-strings) | Medium |
 | <span id="1110">1110</span> | [Delete Nodes And Return Forest](https://leetcode.com/problems/delete-nodes-and-return-forest "删点成林") | [Go](https://github.com/openset/leetcode/tree/master/problems/delete-nodes-and-return-forest) | Medium |
 | <span id="1109">1109</span> | [Corporate Flight Bookings](https://leetcode.com/problems/corporate-flight-bookings "航班预订统计") | [Go](https://github.com/openset/leetcode/tree/master/problems/corporate-flight-bookings) | Medium |

problems/average-selling-price/README.md

@@ -0,0 +1,14 @@
+<!--|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](https://github.com/openset/leetcode/tree/master/problems/check-if-it-is-a-good-array "Check If It Is a Good Array")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/cells-with-odd-values-in-a-matrix "Cells with Odd Values in a Matrix")
+
+## [1251. Average Selling Price (Easy)](https://leetcode.com/problems/average-selling-price "")
+
+

problems/average-selling-price/mysql_schemas.sql

@@ -0,0 +1,12 @@
+Create table If Not Exists Prices (product_id int, start_date date, end_date date, price int);
+Create table If Not Exists UnitsSold (product_id int, purchase_date date, units int);
+Truncate table Prices;
+insert into Prices (product_id, start_date, end_date, price) values ('1', '2019-02-17', '2019-02-28', '5');
+insert into Prices (product_id, start_date, end_date, price) values ('1', '2019-03-01', '2019-03-22', '20');
+insert into Prices (product_id, start_date, end_date, price) values ('2', '2019-02-01', '2019-02-20', '15');
+insert into Prices (product_id, start_date, end_date, price) values ('2', '2019-02-21', '2019-03-31', '30');
+Truncate table UnitsSold;
+insert into UnitsSold (product_id, purchase_date, units) values ('1', '2019-02-25', '100');
+insert into UnitsSold (product_id, purchase_date, units) values ('1', '2019-03-01', '15');
+insert into UnitsSold (product_id, purchase_date, units) values ('2', '2019-02-10', '200');
+insert into UnitsSold (product_id, purchase_date, units) values ('2', '2019-03-22', '30');

problems/cells-with-odd-values-in-a-matrix/README.md

@@ -0,0 +1,60 @@
+<!--|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](https://github.com/openset/leetcode/tree/master/problems/average-selling-price "Average Selling Price")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/reconstruct-a-2-row-binary-matrix "Reconstruct a 2-Row Binary Matrix")
+
+## [1252. Cells with Odd Values in a Matrix (Easy)](https://leetcode.com/problems/cells-with-odd-values-in-a-matrix "奇数值单元格的数目")
+
+<p>Given&nbsp;<code>n</code>&nbsp;and&nbsp;<code>m</code>&nbsp;which are the dimensions of a matrix initialized by zeros and given an array <code>indices</code>&nbsp;where <code>indices[i] = [ri, ci]</code>. For each pair of <code>[ri, ci]</code>&nbsp;you have to increment all cells in row <code>ri</code> and column <code>ci</code>&nbsp;by 1.</p>
+
+<p>Return <em>the number of cells with odd values</em> in the matrix after applying the increment to all <code>indices</code>.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2019/10/30/e1.png" style="width: 600px; height: 118px;" />
+<pre>
+<strong>Input:</strong> n = 2, m = 3, indices = [[0,1],[1,1]]
+<strong>Output:</strong> 6
+<strong>Explanation:</strong> Initial matrix = [[0,0,0],[0,0,0]].
+After applying first increment it becomes [[1,2,1],[0,1,0]].
+The final matrix will be [[1,3,1],[1,3,1]] which contains 6 odd numbers.
+</pre>
+
+<p><strong>Example 2:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2019/10/30/e2.png" style="width: 600px; height: 150px;" />
+<pre>
+<strong>Input:</strong> n = 2, m = 2, indices = [[1,1],[0,0]]
+<strong>Output:</strong> 0
+<strong>Explanation:</strong> Final matrix = [[2,2],[2,2]]. There is no odd number in the final matrix.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= n &lt;= 50</code></li>
+	<li><code>1 &lt;= m &lt;= 50</code></li>
+	<li><code>1 &lt;= indices.length &lt;= 100</code></li>
+	<li><code>0 &lt;= indices[i][0] &lt;&nbsp;n</code></li>
+	<li><code>0 &lt;= indices[i][1] &lt;&nbsp;m</code></li>
+</ul>
+
+### Related Topics
+  [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Simulation : With small constraints, it is possible to apply changes to each row and column and count odd cells after applying it.
+</details>
+
+<details>
+<summary>Hint 2</summary>
+You can accumulate the number you should add to each row and column and then you can count the number of odd cells.
+</details>

problems/check-if-it-is-a-good-array/README.md

@@ -7,7 +7,7 @@
 
 [< Previous](https://github.com/openset/leetcode/tree/master/problems/minimum-remove-to-make-valid-parentheses "Minimum Remove to Make Valid Parentheses")
 
-Next >
+[Next >](https://github.com/openset/leetcode/tree/master/problems/average-selling-price "Average Selling Price")
 
 ## [1250. Check If It Is a Good Array (Hard)](https://leetcode.com/problems/check-if-it-is-a-good-array "检查「好数组」")
 

problems/clone-graph/README.md

@@ -17,7 +17,7 @@
 
 <p><strong>Example:</strong></p>
 
-<p><img alt="" src="https://assets.leetcode.com/uploads/2019/02/19/113_sample.png" style="width: 200px; height: 149px;" /></p>
+<p><img alt="" src="https://assets.leetcode.com/uploads/2019/11/04/133_clone_graph_question.png" style="width: 500px;height:550px" /></p>
 
 <pre>
 <strong>Input:

problems/maximum-score-words-formed-by-letters/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](https://github.com/openset/leetcode/tree/master/problems/number-of-closed-islands "Number of Closed Islands")
+　　　　　　　　　　　　　　　　
+Next >
+
+## [1255. Maximum Score Words Formed by Letters (Hard)](https://leetcode.com/problems/maximum-score-words-formed-by-letters "得分最高的单词集合")
+
+<p>Given a list of <code>words</code>, list of&nbsp; single&nbsp;<code>letters</code> (might be repeating)&nbsp;and <code>score</code>&nbsp;of every character.</p>
+
+<p>Return the maximum score of <strong>any</strong> valid set of words formed by using the given letters (<code>words[i]</code> cannot be used two&nbsp;or more times).</p>
+
+<p>It is not necessary to use all characters in <code>letters</code> and each letter can only be used once. Score of letters&nbsp;<code>&#39;a&#39;</code>, <code>&#39;b&#39;</code>, <code>&#39;c&#39;</code>, ... ,<code>&#39;z&#39;</code> is given by&nbsp;<code>score[0]</code>, <code>score[1]</code>, ... , <code>score[25]</code> respectively.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> words = [&quot;dog&quot;,&quot;cat&quot;,&quot;dad&quot;,&quot;good&quot;], letters = [&quot;a&quot;,&quot;a&quot;,&quot;c&quot;,&quot;d&quot;,&quot;d&quot;,&quot;d&quot;,&quot;g&quot;,&quot;o&quot;,&quot;o&quot;], score = [1,0,9,5,0,0,3,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0]
+<strong>Output:</strong> 23
+<strong>Explanation:</strong>
+Score  a=1, c=9, d=5, g=3, o=2
+Given letters, we can form the words &quot;dad&quot; (5+1+5) and &quot;good&quot; (3+2+2+5) with a score of 23.
+Words &quot;dad&quot; and &quot;dog&quot; only get a score of 21.</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> words = [&quot;xxxz&quot;,&quot;ax&quot;,&quot;bx&quot;,&quot;cx&quot;], letters = [&quot;z&quot;,&quot;a&quot;,&quot;b&quot;,&quot;c&quot;,&quot;x&quot;,&quot;x&quot;,&quot;x&quot;], score = [4,4,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,5,0,10]
+<strong>Output:</strong> 27
+<strong>Explanation:</strong>
+Score  a=4, b=4, c=4, x=5, z=10
+Given letters, we can form the words &quot;ax&quot; (4+5), &quot;bx&quot; (4+5) and &quot;cx&quot; (4+5) with a score of 27.
+Word &quot;xxxz&quot; only get a score of 25.</pre>
+
+<p><strong>Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> words = [&quot;leetcode&quot;], letters = [&quot;l&quot;,&quot;e&quot;,&quot;t&quot;,&quot;c&quot;,&quot;o&quot;,&quot;d&quot;], score = [0,0,1,1,1,0,0,0,0,0,0,1,0,0,1,0,0,0,0,1,0,0,0,0,0,0]
+<strong>Output:</strong> 0
+<strong>Explanation:</strong>
+Letter &quot;e&quot; can only be used once.</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= words.length &lt;= 14</code></li>
+	<li><code>1 &lt;= words[i].length &lt;= 15</code></li>
+	<li><code>1 &lt;= letters.length &lt;= 100</code></li>
+	<li><code>letters[i].length == 1</code></li>
+	<li><code>score.length ==&nbsp;26</code></li>
+	<li><code>0 &lt;= score[i] &lt;= 10</code></li>
+	<li><code>words[i]</code>, <code>letters[i]</code>&nbsp;contains only lower case English letters.</li>
+</ul>
+
+### Related Topics
+  [[Bit Manipulation](https://github.com/openset/leetcode/tree/master/tag/bit-manipulation/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Note that words.length is small. This means you can iterate over every subset of words (2^N).
+</details>

problems/minimum-swaps-to-make-strings-equal/README.md

@@ -9,7 +9,7 @@
 
 [Next >](https://github.com/openset/leetcode/tree/master/problems/count-number-of-nice-subarrays "Count Number of Nice Subarrays")
 
-## [1247. Minimum Swaps to Make Strings Equal (Easy)](https://leetcode.com/problems/minimum-swaps-to-make-strings-equal "交换字符使得字符串相同")
+## [1247. Minimum Swaps to Make Strings Equal (Medium)](https://leetcode.com/problems/minimum-swaps-to-make-strings-equal "交换字符使得字符串相同")
 
 <p>You are given two strings&nbsp;<code>s1</code>&nbsp;and&nbsp;<code>s2</code>&nbsp;of equal length&nbsp;consisting of letters <code>&quot;x&quot;</code> and <code>&quot;y&quot;</code> <strong>only</strong>. Your task is to&nbsp;make these two strings equal to each other. You can swap any two characters that belong to <strong>different</strong> strings,&nbsp;which means: swap <code>s1[i]</code> and <code>s2[j]</code>.</p>
 

problems/number-of-closed-islands/README.md

@@ -0,0 +1,71 @@
+<!--|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](https://github.com/openset/leetcode/tree/master/problems/reconstruct-a-2-row-binary-matrix "Reconstruct a 2-Row Binary Matrix")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/maximum-score-words-formed-by-letters "Maximum Score Words Formed by Letters")
+
+## [1254. Number of Closed Islands (Medium)](https://leetcode.com/problems/number-of-closed-islands "统计封闭岛屿的数目")
+
+<p>Given a 2D&nbsp;<code>grid</code> consists of <code>0s</code> (land)&nbsp;and <code>1s</code> (water).&nbsp; An <em>island</em> is a maximal 4-directionally connected group of <code><font face="monospace">0</font>s</code> and a <em>closed island</em>&nbsp;is an island <strong>totally</strong>&nbsp;(all left, top, right, bottom) surrounded by <code>1s.</code></p>
+
+<p>Return the number of <em>closed islands</em>.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_3_1610.png" style="width: 240px; height: 120px;" /></p>
+
+<pre>
+<strong>Input:</strong> grid = [[1,1,1,1,1,1,1,0],[1,0,0,0,0,1,1,0],[1,0,1,0,1,1,1,0],[1,0,0,0,0,1,0,1],[1,1,1,1,1,1,1,0]]
+<strong>Output:</strong> 2
+<strong>Explanation:</strong> 
+Islands in gray are closed because they are completely surrounded by water (group of 1s).</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_4_1610.png" style="width: 160px; height: 80px;" /></p>
+
+<pre>
+<strong>Input:</strong> grid = [[0,0,1,0,0],[0,1,0,1,0],[0,1,1,1,0]]
+<strong>Output:</strong> 1
+</pre>
+
+<p><strong>Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> grid = [[1,1,1,1,1,1,1],
+&nbsp;              [1,0,0,0,0,0,1],
+&nbsp;              [1,0,1,1,1,0,1],
+&nbsp;              [1,0,1,0,1,0,1],
+&nbsp;              [1,0,1,1,1,0,1],
+&nbsp;              [1,0,0,0,0,0,1],
+               [1,1,1,1,1,1,1]]
+<strong>Output:</strong> 2
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= grid.length, grid[0].length &lt;= 100</code></li>
+	<li><code>0 &lt;= grid[i][j] &lt;=1</code></li>
+</ul>
+
+### Related Topics
+  [[Depth-first Search](https://github.com/openset/leetcode/tree/master/tag/depth-first-search/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Exclude connected group of 0s on the corners because they are not closed island.
+</details>
+
+<details>
+<summary>Hint 2</summary>
+Return number of connected component of 0s on the grid.
+</details>