awesee · awesee · May 6, 2020 · May 6, 2020
diff --git a/README.md b/README.md
@@ -62,7 +62,21 @@ LeetCode Problems' Solutions
 
 | # | Title | Solution | Difficulty |
 | :-: | - | - | :-: |
-| <span id="1425">1425</span> | [Constrained Subset Sum](https://leetcode.com/problems/constrained-subset-sum "带限制的子序列和") | [Go](problems/constrained-subset-sum) | Hard |
+| <span id="1439">1439</span> | [Find the Kth Smallest Sum of a Matrix With Sorted Rows](https://leetcode.com/problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows "有序矩阵中的第 k 个最小数组和") | [Go](problems/find-the-kth-smallest-sum-of-a-matrix-with-sorted-rows) | Hard |
+| <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="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="1428">1428</span> | [Leftmost Column with at Least a One](https://leetcode.com/problems/leftmost-column-with-at-least-a-one) 🔒 | [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) 🔒 | [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 |
+| <span id="1425">1425</span> | [Constrained Subsequence Sum](https://leetcode.com/problems/constrained-subsequence-sum "带限制的子序列和") | [Go](problems/constrained-subsequence-sum) | Hard |
 | <span id="1424">1424</span> | [Diagonal Traverse II](https://leetcode.com/problems/diagonal-traverse-ii "对角线遍历 II") | [Go](problems/diagonal-traverse-ii) | Medium |
 | <span id="1423">1423</span> | [Maximum Points You Can Obtain from Cards](https://leetcode.com/problems/maximum-points-you-can-obtain-from-cards "可获得的最大点数") | [Go](problems/maximum-points-you-can-obtain-from-cards) | Medium |
 | <span id="1422">1422</span> | [Maximum Score After Splitting a String](https://leetcode.com/problems/maximum-score-after-splitting-a-string "分割字符串的最大得分") | [Go](problems/maximum-score-after-splitting-a-string) | Easy |

diff --git a/problems/check-if-a-string-can-break-another-string/README.md b/problems/check-if-a-string-can-break-another-string/README.md
@@ -0,0 +1,60 @@
+<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    openset <[email protected]>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+[< Previous](../max-difference-you-can-get-from-changing-an-integer "Max Difference You Can Get From Changing an Integer")
+
+[Next >](../number-of-ways-to-wear-different-hats-to-each-other "Number of Ways to Wear Different Hats to Each Other")
+
+## [1433. Check If a String Can Break Another String (Medium)](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")
+
+<p>Given two strings: <code>s1</code> and <code>s2</code> with the same&nbsp;size, check if some&nbsp;permutation of string <code>s1</code> can break&nbsp;some&nbsp;permutation of string <code>s2</code> or vice-versa (in other words <code>s2</code> can break <code>s1</code>).</p>
+
+<p>A string <code>x</code>&nbsp;can break&nbsp;string <code>y</code>&nbsp;(both of size <code>n</code>) if <code>x[i] &gt;= y[i]</code>&nbsp;(in alphabetical order)&nbsp;for all <code>i</code>&nbsp;between <code>0</code> and <code>n-1</code>.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> s1 = &quot;abc&quot;, s2 = &quot;xya&quot;
+<strong>Output:</strong> true
+<strong>Explanation:</strong> &quot;ayx&quot; is a permutation of s2=&quot;xya&quot; which can break to string &quot;abc&quot; which is a permutation of s1=&quot;abc&quot;.
+</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> s1 = &quot;abe&quot;, s2 = &quot;acd&quot;
+<strong>Output:</strong> false 
+<strong>Explanation:</strong> All permutations for s1=&quot;abe&quot; are: &quot;abe&quot;, &quot;aeb&quot;, &quot;bae&quot;, &quot;bea&quot;, &quot;eab&quot; and &quot;eba&quot; and all permutation for s2=&quot;acd&quot; are: &quot;acd&quot;, &quot;adc&quot;, &quot;cad&quot;, &quot;cda&quot;, &quot;dac&quot; and &quot;dca&quot;. However, there is not any permutation from s1 which can break some permutation from s2 and vice-versa.
+</pre>
+
+<p><strong>Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> s1 = &quot;leetcodee&quot;, s2 = &quot;interview&quot;
+<strong>Output:</strong> true
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>s1.length == n</code></li>
+	<li><code>s2.length == n</code></li>
+	<li><code>1 &lt;= n &lt;= 10^5</code></li>
+	<li>All strings consist of lowercase English letters.</li>
+</ul>
+
+### Related Topics
+  [[Greedy](../../tag/greedy/README.md)]
+  [[String](../../tag/string/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Sort both strings and then check if one of them can break the other.
+</details>
diff --git a/...-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/README.md b/...-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/README.md
@@ -0,0 +1,28 @@
+<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    openset <[email protected]>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+[< Previous](../first-unique-number "First Unique Number")
+
+[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 "")
+
+
+
+### Related Topics
+  [[Tree](../../tag/tree/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Depth-first search (DFS) with the parameters: current node in the binary tree and current position in the array of integers.
+</details>
+
+<details>
+<summary>Hint 2</summary>
+When reaching at final position check if it is a leaf node.
+</details>
diff --git a/problems/check-if-all-1s-are-at-least-length-k-places-away/README.md b/problems/check-if-all-1s-are-at-least-length-k-places-away/README.md
@@ -0,0 +1,66 @@
+<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    openset <[email protected]>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+[< Previous](../destination-city "Destination City")
+
+[Next >](../longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit "Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit")
+
+## [1437. Check If All 1's Are at Least Length K Places Away (Medium)](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")
+
+<p>Given an array <code>nums</code> of 0s and 1s and an integer <code>k</code>, return <code>True</code> if all 1&#39;s are at least <code>k</code> places away from each other, otherwise return <code>False</code>.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/04/15/sample_1_1791.png" style="width: 214px; height: 90px;" /></strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [1,0,0,0,1,0,0,1], k = 2
+<strong>Output:</strong> true
+<strong>Explanation:</strong> Each of the 1s are at least 2 places away from each other.
+</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/04/15/sample_2_1791.png" style="width: 160px; height: 86px;" /></strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [1,0,0,1,0,1], k = 2
+<strong>Output:</strong> false
+<strong>Explanation: </strong>The second 1 and third 1 are only one apart from each other.</pre>
+
+<p><strong>Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [1,1,1,1,1], k = 0
+<strong>Output:</strong> true
+</pre>
+
+<p><strong>Example 4:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [0,1,0,1], k = 1
+<strong>Output:</strong> true
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= nums.length &lt;= 10^5</code></li>
+	<li><code>0 &lt;= k &lt;= nums.length</code></li>
+	<li><code>nums[i]</code>&nbsp;is&nbsp;<code>0</code>&nbsp;or&nbsp;<code>1</code></li>
+</ul>
+
+### Related Topics
+  [[Array](../../tag/array/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Each time you find a number 1, check whether or not it is K or more places away from the next one. If it's not, return false.
+</details>
diff --git a/problems/constrained-subsequence-sum/README.md b/problems/constrained-subsequence-sum/README.md
@@ -0,0 +1,73 @@
+<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    openset <[email protected]>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+[< Previous](../diagonal-traverse-ii "Diagonal Traverse II")
+
+[Next >](../counting-elements "Counting Elements")
+
+## [1425. Constrained Subsequence Sum (Hard)](https://leetcode.com/problems/constrained-subsequence-sum "带限制的子序列和")
+
+<p>Given an integer array&nbsp;<code>nums</code>&nbsp;and an integer <code>k</code>, return the maximum sum of a <strong>non-empty</strong> subsequence&nbsp;of that array such that for every&nbsp;two <strong>consecutive</strong> integers in the subsequence,&nbsp;<code>nums[i]</code>&nbsp;and&nbsp;<code>nums[j]</code>, where&nbsp;<code>i &lt; j</code>, the condition&nbsp;<code>j - i &lt;= k</code>&nbsp;is satisfied.</p>
+
+<p>A&nbsp;<em>subsequence</em>&nbsp;of an array is&nbsp;obtained by deleting some number of elements (can be&nbsp;zero) from the array, leaving the remaining elements in their original order.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [10,2,-10,5,20], k = 2
+<strong>Output:</strong> 37
+<b>Explanation:</b> The subsequence is [10, 2, 5, 20].
+</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [-1,-2,-3], k = 1
+<strong>Output:</strong> -1
+<b>Explanation:</b> The subsequence must be non-empty, so we choose the largest number.
+</pre>
+
+<p><strong>Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [10,-2,-10,-5,20], k = 2
+<strong>Output:</strong> 23
+<b>Explanation:</b> The subsequence is [10, -2, -5, 20].
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= k &lt;= nums.length &lt;= 10^5</code></li>
+	<li><code>-10^4&nbsp;&lt;= nums[i] &lt;= 10^4</code></li>
+</ul>
+
+### Related Topics
+  [[Dynamic Programming](../../tag/dynamic-programming/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Use dynamic programming.
+</details>
+
+<details>
+<summary>Hint 2</summary>
+Let dp[i] be the solution for the prefix of the array that ends at index i, if the element at index i is in the subsequence.
+</details>
+
+<details>
+<summary>Hint 3</summary>
+dp[i] = nums[i] + max(0, dp[i-k], dp[i-k+1], ..., dp[i-1])
+</details>
+
+<details>
+<summary>Hint 4</summary>
+Use a heap with the sliding window technique to optimize the dp.
+</details>
diff --git a/problems/construct-binary-search-tree-from-preorder-traversal/README.md b/problems/construct-binary-search-tree-from-preorder-traversal/README.md
@@ -15,7 +15,7 @@
 
 <p><em>(Recall that a binary search tree&nbsp;is a binary tree where for every <font face="monospace">node</font>, any descendant of <code>node.left</code> has a value <code>&lt;</code>&nbsp;<code>node.val</code>, and any descendant of <code>node.right</code> has a value <code>&gt;</code>&nbsp;<code>node.val</code>.&nbsp; Also recall that a preorder traversal&nbsp;displays the value of the&nbsp;<code>node</code> first, then traverses <code>node.left</code>, then traverses <code>node.right</code>.)</em></p>
 
-<p>&nbsp;</p>
+<p>It&#39;s guaranteed that for the given test cases there is always possible to find a binary search tree with the given requirements.</p>
 
 <p><strong>Example 1:</strong></p>
 
@@ -26,13 +26,13 @@
 </pre>
 
 <p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
 
-<p><strong>Note:</strong>&nbsp;</p>
-
-<ol>
+<ul>
 	<li><code>1 &lt;= preorder.length &lt;= 100</code></li>
+	<li><code>1 &lt;= preorder[i]&nbsp;&lt;= 10^8</code></li>
 	<li>The values of <code>preorder</code> are distinct.</li>
-</ol>
+</ul>
 
 ### Related Topics
   [[Tree](../../tag/tree/README.md)]
diff --git a/problems/counting-elements/README.md b/problems/counting-elements/README.md
@@ -0,0 +1,28 @@
+<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    openset <[email protected]>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+[< Previous](../constrained-subsequence-sum "Constrained Subsequence Sum")
+
+[Next >](../perform-string-shifts "Perform String Shifts")
+
+## [1426. Counting Elements (Easy)](https://leetcode.com/problems/counting-elements "数元素")
+
+
+
+### Related Topics
+  [[Array](../../tag/array/README.md)]
+
+### Hints
+<details>
+<summary>Hint 1</summary>
+Use hashset to store all elements.
+</details>
+
+<details>
+<summary>Hint 2</summary>
+Loop again to count all valid elements.
+</details>
diff --git a/problems/create-a-session-bar-chart/README.md b/problems/create-a-session-bar-chart/README.md
@@ -0,0 +1,14 @@
+<!--|This file generated by command(leetcode description); DO NOT EDIT.    |-->
+<!--+----------------------------------------------------------------------+-->
+<!--|@author    openset <[email protected]>                           |-->
+<!--|@link      https://github.com/openset                                 |-->
+<!--|@home      https://github.com/openset/leetcode                        |-->
+<!--+----------------------------------------------------------------------+-->
+
+[< Previous](../number-of-ways-to-wear-different-hats-to-each-other "Number of Ways to Wear Different Hats to Each Other")
+
+[Next >](../destination-city "Destination City")
+
+## [1435. Create a Session Bar Chart (Easy)](https://leetcode.com/problems/create-a-session-bar-chart "")
+
+
diff --git a/problems/create-a-session-bar-chart/mysql_schemas.sql b/problems/create-a-session-bar-chart/mysql_schemas.sql
@@ -0,0 +1,7 @@
+Create table If Not Exists Sessions (session_id int, duration int);
+Truncate table Sessions;
+insert into Sessions (session_id, duration) values ('1', '30');
+insert into Sessions (session_id, duration) values ('2', '199');
+insert into Sessions (session_id, duration) values ('3', '299');
+insert into Sessions (session_id, duration) values ('4', '580');
+insert into Sessions (session_id, duration) values ('5', '1000');