Add: Related Topics

Author: Openset

problems/01-matrix/README.md

@@ -49,3 +49,7 @@ Output:
 <li>The cells are adjacent in only four directions: up, down, left and right.</li>
 </ol>
 </p>
+
+
+### Related Topics
+[[Depth-first Search](https://github.com/openset/leetcode/tree/master/tag/depth-first-search/README.md)] [[Breadth-first Search](https://github.com/openset/leetcode/tree/master/tag/breadth-first-search/README.md)] 

problems/1-bit-and-2-bit-characters/README.md

@@ -36,5 +36,11 @@ The only way to decode it is two-bit character and two-bit character. So the las
 <li><code>bits[i]</code> is always <code>0</code> or <code>1</code>.</li>
 </p>
 
+### Related Topics
+[[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)] 
+
 ### Similar Questions
   1. [Gray Code](https://github.com/openset/leetcode/tree/master/problems/gray-code) (Medium)
+
+### Hints
+  1. Keep track of where the next character starts.  At the end, you want to know if you started on the last bit.

problems/132-pattern/README.md

@@ -41,4 +41,7 @@ that <b>i</b> < <b>j</b> < <b>k</b> and a<sub><b>i</b></sub> < a<sub><b>k</b></s
 
 <b>Explanation:</b> There are three 132 patterns in the sequence: [-1, 3, 2], [-1, 3, 0] and [-1, 2, 0].
 </pre>
-</p>
+</p>
+
+### Related Topics
+[[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)] 

problems/2-keys-keyboard/README.md

@@ -38,5 +38,11 @@ In step 3, we use <b>Paste</b> operation to get 'AAA'.
 </ol>
 </p>
 
+### Related Topics
+[[Dynamic Programming](https://github.com/openset/leetcode/tree/master/tag/dynamic-programming/README.md)] 
+
 ### Similar Questions
   1. [4 Keys Keyboard](https://github.com/openset/leetcode/tree/master/problems/4-keys-keyboard) (Medium)
+
+### Hints
+  1. How many characters may be there in the clipboard at the last step if n = 3? n = 7? n = 10? n = 24?

problems/24-game/README.md

@@ -33,4 +33,7 @@ You have 4 cards each containing a number from 1 to 9.  You need to judge whethe
 <li>You cannot concatenate numbers together.  For example, if the input is <code>[1, 2, 1, 2]</code>, we cannot write this as 12 + 12.</li>
 </ol>
 </p>
-</p>
+</p>
+
+### Related Topics
+[[Depth-first Search](https://github.com/openset/leetcode/tree/master/tag/depth-first-search/README.md)] 

problems/3sum-closest/README.md

@@ -18,6 +18,9 @@ The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
 </pre>
 
 
+### Related Topics
+[[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)] [[Two Pointers](https://github.com/openset/leetcode/tree/master/tag/two-pointers/README.md)] 
+
 ### Similar Questions
   1. [3Sum](https://github.com/openset/leetcode/tree/master/problems/3sum) (Medium)
   1. [3Sum Smaller](https://github.com/openset/leetcode/tree/master/problems/3sum-smaller) (Medium)

problems/3sum-with-multiplicity/README.md

@@ -47,4 +47,7 @@ and two 2s from [2,2,2,2] in 6 ways.
 	<li><code>3 &lt;= A.length &lt;= 3000</code></li>
 	<li><code>0 &lt;= A[i] &lt;= 100</code></li>
 	<li><code>0 &lt;= target &lt;= 300</code></li>
-</ol>
+</ol>
+
+### Related Topics
+[[Two Pointers](https://github.com/openset/leetcode/tree/master/tag/two-pointers/README.md)] 

problems/3sum/README.md

@@ -26,6 +26,9 @@ A solution set is:
 </pre>
 
 
+### Related Topics
+[[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)] [[Two Pointers](https://github.com/openset/leetcode/tree/master/tag/two-pointers/README.md)] 
+
 ### Similar Questions
   1. [Two Sum](https://github.com/openset/leetcode/tree/master/problems/two-sum) (Easy)
   1. [3Sum Closest](https://github.com/openset/leetcode/tree/master/problems/3sum-closest) (Medium)

problems/4sum-ii/README.md

@@ -29,5 +29,8 @@ The two tuples are:
 </pre>
 </p>
 
+### Related Topics
+[[Hash Table](https://github.com/openset/leetcode/tree/master/tag/hash-table/README.md)] [[Binary Search](https://github.com/openset/leetcode/tree/master/tag/binary-search/README.md)] 
+
 ### Similar Questions
   1. [4Sum](https://github.com/openset/leetcode/tree/master/problems/4sum) (Medium)

problems/4sum/README.md

@@ -27,6 +27,9 @@ A solution set is:
 </pre>
 
 
+### 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)] [[Two Pointers](https://github.com/openset/leetcode/tree/master/tag/two-pointers/README.md)] 
+
 ### Similar Questions
   1. [Two Sum](https://github.com/openset/leetcode/tree/master/problems/two-sum) (Easy)
   1. [3Sum](https://github.com/openset/leetcode/tree/master/problems/3sum) (Medium)