Merge pull request #602 from openset/develop

Update:  description

Author: Shuo

problems/binary-tree-inorder-traversal/README.md

@@ -28,9 +28,9 @@
 <p><strong>Follow up:</strong> Recursive solution is trivial, could you do it iteratively?</p>
 
 ### Related Topics
-  [[Hash Table](https://github.com/openset/leetcode/tree/master/tag/hash-table/README.md)]
   [[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)]
   [[Tree](https://github.com/openset/leetcode/tree/master/tag/tree/README.md)]
+  [[Hash Table](https://github.com/openset/leetcode/tree/master/tag/hash-table/README.md)]
 
 ### Similar Questions
   1. [Validate Binary Search Tree](https://github.com/openset/leetcode/tree/master/problems/validate-binary-search-tree) (Medium)

problems/construct-binary-tree-from-inorder-and-postorder-traversal/README.md

@@ -33,9 +33,9 @@ postorder = [9,15,7,20,3]</pre>
 </pre>
 
 ### Related Topics
-  [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)]
   [[Tree](https://github.com/openset/leetcode/tree/master/tag/tree/README.md)]
   [[Depth-first Search](https://github.com/openset/leetcode/tree/master/tag/depth-first-search/README.md)]
+  [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)]
 
 ### Similar Questions
   1. [Construct Binary Tree from Preorder and Inorder Traversal](https://github.com/openset/leetcode/tree/master/problems/construct-binary-tree-from-preorder-and-inorder-traversal) (Medium)

problems/construct-binary-tree-from-preorder-and-inorder-traversal/README.md

@@ -32,9 +32,9 @@ inorder = [9,3,15,20,7]</pre>
    15   7</pre>
 
 ### Related Topics
-  [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)]
   [[Tree](https://github.com/openset/leetcode/tree/master/tag/tree/README.md)]
   [[Depth-first Search](https://github.com/openset/leetcode/tree/master/tag/depth-first-search/README.md)]
+  [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)]
 
 ### Similar Questions
   1. [Construct Binary Tree from Inorder and Postorder Traversal](https://github.com/openset/leetcode/tree/master/problems/construct-binary-tree-from-inorder-and-postorder-traversal) (Medium)

problems/encode-and-decode-strings/README.md

@@ -11,7 +11,49 @@
 
 ## 271. Encode and Decode Strings (Medium)
 
+<p>Design an algorithm to encode <b>a list of strings</b> to <b>a string</b>. The encoded string is then sent over the network and is decoded back to the original list of strings.</p>
 
+<p>Machine 1 (sender) has the function:</p>
+
+<pre>
+string encode(vector&lt;string&gt; strs) {
+  // ... your code
+  return encoded_string;
+}</pre>
+Machine 2 (receiver) has the function:
+
+<pre>
+vector&lt;string&gt; decode(string s) {
+  //... your code
+  return strs;
+}
+</pre>
+
+<p>So Machine 1 does:</p>
+
+<pre>
+string encoded_string = encode(strs);
+</pre>
+
+<p>and Machine 2 does:</p>
+
+<pre>
+vector&lt;string&gt; strs2 = decode(encoded_string);
+</pre>
+
+<p><code>strs2</code> in Machine 2 should be the same as <code>strs</code> in Machine 1.</p>
+
+<p>Implement the <code>encode</code> and <code>decode</code> methods.</p>
+
+<p>&nbsp;</p>
+
+<p><b>Note:</b></p>
+
+<ul>
+	<li>The string may contain any possible characters out of 256 valid ascii characters. Your algorithm should be generalized enough to work on any possible characters.</li>
+	<li>Do not use class member/global/static variables to store states. Your encode and decode algorithms should be stateless.</li>
+	<li>Do not rely on any library method such as <code>eval</code> or serialize methods. You should implement your own encode/decode algorithm.</li>
+</ul>
 
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   [[String](https://github.com/openset/leetcode/tree/master/tag/string/README.md)]

problems/largest-rectangle-in-histogram/README.md

@@ -33,8 +33,8 @@
 </pre>
 
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   [[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)]
+  [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)]
 
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problems/maximal-rectangle/README.md

@@ -27,10 +27,10 @@
 </pre>
 
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+  [[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)]
   [[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)]
   [[Dynamic Programming](https://github.com/openset/leetcode/tree/master/tag/dynamic-programming/README.md)]
-  [[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)]
 
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problems/subsets/README.md

@@ -32,9 +32,9 @@
 ]</pre>
 
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+  [[Bit Manipulation](https://github.com/openset/leetcode/tree/master/tag/bit-manipulation/README.md)]
   [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)]
   [[Backtracking](https://github.com/openset/leetcode/tree/master/tag/backtracking/README.md)]
-  [[Bit Manipulation](https://github.com/openset/leetcode/tree/master/tag/bit-manipulation/README.md)]
 
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problems/unique-binary-search-trees-ii/README.md

@@ -36,8 +36,8 @@ The above output corresponds to the 5 unique BST's shown below:
 </pre>
 
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   [[Tree](https://github.com/openset/leetcode/tree/master/tag/tree/README.md)]
+  [[Dynamic Programming](https://github.com/openset/leetcode/tree/master/tag/dynamic-programming/README.md)]
 
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problems/unique-binary-search-trees/README.md

@@ -29,8 +29,8 @@
 </pre>
 
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   [[Tree](https://github.com/openset/leetcode/tree/master/tag/tree/README.md)]
+  [[Dynamic Programming](https://github.com/openset/leetcode/tree/master/tag/dynamic-programming/README.md)]
 
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