Add: new

Author: openset

Diff for: problems/3sum-smaller/README.md

@@ -21,3 +21,4 @@
   1. [3Sum](https://github.com/openset/leetcode/tree/master/problems/3sum) (Medium)
   1. [3Sum Closest](https://github.com/openset/leetcode/tree/master/problems/3sum-closest) (Medium)
   1. [Valid Triangle Number](https://github.com/openset/leetcode/tree/master/problems/valid-triangle-number) (Medium)
+  1. [Two Sum Less Than K](https://github.com/openset/leetcode/tree/master/problems/two-sum-less-than-k) (Easy)

Diff for: problems/construct-quad-tree/README.md

@@ -9,7 +9,7 @@
 
 [Next >](https://github.com/openset/leetcode/tree/master/problems/serialize-and-deserialize-n-ary-tree "Serialize and Deserialize N-ary Tree")
 
-## 427. Construct Quad Tree (Easy)
+## 427. Construct Quad Tree (Medium)
 
 <p>We want to use quad trees to store an <code>N x N</code> boolean grid. Each cell in the grid can only be true or false. The root node represents the whole grid. For each node, it will be subdivided into four children nodes <strong>until the values in the region it represents are all the same</strong>.</p>
 

Diff for: problems/decode-string/README.md

@@ -11,25 +11,23 @@
 
 ## 394. Decode String (Medium)
 
-<p>
-Given an encoded string, return it's decoded string.
-</p>
-<p>
-The encoding rule is: <code>k[encoded_string]</code>, where the <i>encoded_string</i> inside the square brackets is being repeated exactly <i>k</i> times. Note that <i>k</i> is guaranteed to be a positive integer.</p>
+<p>Given an encoded string, return its decoded string.</p>
 
-<p>
-You may assume that the input string is always valid; No extra white spaces, square brackets are well-formed, etc.</p>
+<p>The encoding rule is: <code>k[encoded_string]</code>, where the <i>encoded_string</i> inside the square brackets is being repeated exactly <i>k</i> times. Note that <i>k</i> is guaranteed to be a positive integer.</p>
 
-<p>Furthermore, you may assume that the original data does not contain any digits and that digits are only for those repeat numbers, <i>k</i>. For example, there won't be input like <code>3a</code> or <code>2[4]</code>.
-</p>
+<p>You may assume that the input string is always valid; No extra white spaces, square brackets are well-formed, etc.</p>
+
+<p>Furthermore, you may assume that the original data does not contain any digits and that digits are only for those repeat numbers, <i>k</i>. For example, there won&#39;t be input like <code>3a</code> or <code>2[4]</code>.</p>
+
+<p><b>Examples:</b></p>
 
-<p><b>Examples:</b>
 <pre>
-s = "3[a]2[bc]", return "aaabcbc".
-s = "3[a2[c]]", return "accaccacc".
-s = "2[abc]3[cd]ef", return "abcabccdcdcdef".
+s = &quot;3[a]2[bc]&quot;, return &quot;aaabcbc&quot;.
+s = &quot;3[a2[c]]&quot;, return &quot;accaccacc&quot;.
+s = &quot;2[abc]3[cd]ef&quot;, return &quot;abcabccdcdcdef&quot;.
 </pre>
-</p>
+
+<p>&nbsp;</p>
 
 ### Related Topics
   [[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)]
@@ -38,4 +36,4 @@ s = "2[abc]3[cd]ef", return "abcabccdcdcdef".
 ### Similar Questions
   1. [Encode String with Shortest Length](https://github.com/openset/leetcode/tree/master/problems/encode-string-with-shortest-length) (Hard)
   1. [Number of Atoms](https://github.com/openset/leetcode/tree/master/problems/number-of-atoms) (Hard)
-  1. [Permutation of Letters](https://github.com/openset/leetcode/tree/master/problems/permutation-of-letters) (Medium)
+  1. [Brace Expansion](https://github.com/openset/leetcode/tree/master/problems/brace-expansion) (Medium)

Diff for: problems/linked-list-cycle-ii/README.md

@@ -51,7 +51,7 @@
 
 <p>&nbsp;</p>
 
-<p><b>Follow up</b>:<br />
+<p><b>Follow-up</b>:<br />
 Can you solve it without using extra space?</p>
 
 ### Related Topics

Diff for: problems/lru-cache/README.md

@@ -9,7 +9,7 @@
 
 [Next >](https://github.com/openset/leetcode/tree/master/problems/insertion-sort-list "Insertion Sort List")
 
-## 146. LRU Cache (Hard)
+## 146. LRU Cache (Medium)
 
 <p>Design and implement a data structure for <a href="https://en.wikipedia.org/wiki/Cache_replacement_policies#LRU" target="_blank">Least Recently Used (LRU) cache</a>. It should support the following operations: <code>get</code> and <code>put</code>.</p>
 

Diff for: problems/min-stack/README.md

@@ -11,36 +11,31 @@
 
 ## 155. Min Stack (Easy)
 
-<p>
-Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.
+<p>Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.</p>
+
 <ul>
-<li>
-push(x) -- Push element x onto stack.
-</li>
-<li>
-pop() -- Removes the element on top of the stack.
-</li>
-<li>
-top() -- Get the top element.
-</li>
-<li>
-getMin() -- Retrieve the minimum element in the stack.
-</li>
+	<li>push(x) -- Push element x onto stack.</li>
+	<li>pop() -- Removes the element on top of the stack.</li>
+	<li>top() -- Get the top element.</li>
+	<li>getMin() -- Retrieve the minimum element in the stack.</li>
 </ul>
-</p>
 
-<p><b>Example:</b><br />
+<p>&nbsp;</p>
+
+<p><b>Example:</b></p>
+
 <pre>
 MinStack minStack = new MinStack();
 minStack.push(-2);
 minStack.push(0);
 minStack.push(-3);
-minStack.getMin();   --> Returns -3.
+minStack.getMin();   --&gt; Returns -3.
 minStack.pop();
-minStack.top();      --> Returns 0.
-minStack.getMin();   --> Returns -2.
+minStack.top();      --&gt; Returns 0.
+minStack.getMin();   --&gt; Returns -2.
 </pre>
-</p>
+
+<p>&nbsp;</p>
 
 ### Related Topics
   [[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)]

Diff for: problems/pacific-atlantic-water-flow/README.md

@@ -11,19 +11,23 @@
 
 ## 417. Pacific Atlantic Water Flow (Medium)
 
-<p>Given an <code>m x n</code> matrix of non-negative integers representing the height of each unit cell in a continent, the "Pacific ocean" touches the left and top edges of the matrix and the "Atlantic ocean" touches the right and bottom edges.</p>
+<p>Given an <code>m x n</code> matrix of non-negative integers representing the height of each unit cell in a continent, the &quot;Pacific ocean&quot; touches the left and top edges of the matrix and the &quot;Atlantic ocean&quot; touches the right and bottom edges.</p>
 
 <p>Water can only flow in four directions (up, down, left, or right) from a cell to another one with height equal or lower.</p>
 
 <p>Find the list of grid coordinates where water can flow to both the Pacific and Atlantic ocean.</p>
 
-<p><b>Note:</b><br />
+<p><b>Note:</b></p>
+
 <ol>
-<li>The order of returned grid coordinates does not matter.</li>
-<li>Both <i>m</i> and <i>n</i> are less than 150.</li>
+	<li>The order of returned grid coordinates does not matter.</li>
+	<li>Both <i>m</i> and <i>n</i> are less than 150.</li>
 </ol>
-</p>
-<p><b>Example:</b>
+
+<p>&nbsp;</p>
+
+<p><b>Example:</b></p>
+
 <pre>
 Given the following 5x5 matrix:
 
@@ -39,7 +43,8 @@ Return:
 
 [[0, 4], [1, 3], [1, 4], [2, 2], [3, 0], [3, 1], [4, 0]] (positions with parentheses in above matrix).
 </pre>
-</p>
+
+<p>&nbsp;</p>
 
 ### Related Topics
   [[Depth-first Search](https://github.com/openset/leetcode/tree/master/tag/depth-first-search/README.md)]

Diff for: problems/two-sum-ii-input-array-is-sorted/README.md

@@ -37,3 +37,4 @@
 ### Similar Questions
   1. [Two Sum](https://github.com/openset/leetcode/tree/master/problems/two-sum) (Easy)
   1. [Two Sum IV - Input is a BST](https://github.com/openset/leetcode/tree/master/problems/two-sum-iv-input-is-a-bst) (Easy)
+  1. [Two Sum Less Than K](https://github.com/openset/leetcode/tree/master/problems/two-sum-less-than-k) (Easy)

Diff for: problems/two-sum/README.md

@@ -24,8 +24,6 @@ Because nums[<strong>0</strong>] + nums[<strong>1</strong>] = 2 + 7 = 9,
 return [<strong>0</strong>, <strong>1</strong>].
 </pre>
 
-<p>&nbsp;</p>
-
 ### Related Topics
   [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)]
   [[Hash Table](https://github.com/openset/leetcode/tree/master/tag/hash-table/README.md)]
@@ -37,3 +35,4 @@ return [<strong>0</strong>, <strong>1</strong>].
   1. [Two Sum III - Data structure design](https://github.com/openset/leetcode/tree/master/problems/two-sum-iii-data-structure-design) (Easy)
   1. [Subarray Sum Equals K](https://github.com/openset/leetcode/tree/master/problems/subarray-sum-equals-k) (Medium)
   1. [Two Sum IV - Input is a BST](https://github.com/openset/leetcode/tree/master/problems/two-sum-iv-input-is-a-bst) (Easy)
+  1. [Two Sum Less Than K](https://github.com/openset/leetcode/tree/master/problems/two-sum-less-than-k) (Easy)