Add: Related Topics

Author: Openset

Diff for: 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)] 

Diff for: 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.

Diff for: 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)] 

Diff for: 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?

Diff for: 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)] 

Diff for: 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)

Diff for: 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)] 

Diff for: 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)

Diff for: 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)

Diff for: 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)

Diff for: problems/accounts-merge/README.md

@@ -32,7 +32,13 @@ We could return these lists in any order, for example the answer [['Mary', 'mary
 <li>The length of <code>accounts[i][j]</code> will be in the range <code>[1, 30]</code>.</li>
 </p>
 
+### Related Topics
+[[Depth-first Search](https://github.com/openset/leetcode/tree/master/tag/depth-first-search/README.md)] [[Union Find](https://github.com/openset/leetcode/tree/master/tag/union-find/README.md)] 
+
 ### Similar Questions
   1. [Redundant Connection](https://github.com/openset/leetcode/tree/master/problems/redundant-connection) (Medium)
   1. [Sentence Similarity](https://github.com/openset/leetcode/tree/master/problems/sentence-similarity) (Easy)
   1. [Sentence Similarity II](https://github.com/openset/leetcode/tree/master/problems/sentence-similarity-ii) (Medium)
+
+### Hints
+  1. For every pair of emails in the same account, draw an edge between those emails.  The problem is about enumerating the connected components of this graph.

Diff for: problems/add-and-search-word-data-structure-design/README.md

@@ -32,6 +32,12 @@ search("b..") -> true
 You may assume that all words are consist of lowercase letters <code>a-z</code>.</p>
 
 
+### Related Topics
+[[Design](https://github.com/openset/leetcode/tree/master/tag/design/README.md)] [[Trie](https://github.com/openset/leetcode/tree/master/tag/trie/README.md)] [[Backtracking](https://github.com/openset/leetcode/tree/master/tag/backtracking/README.md)] 
+
 ### Similar Questions
   1. [Implement Trie (Prefix Tree)](https://github.com/openset/leetcode/tree/master/problems/implement-trie-prefix-tree) (Medium)
   1. [Prefix and Suffix Search](https://github.com/openset/leetcode/tree/master/problems/prefix-and-suffix-search) (Hard)
+
+### Hints
+  1. You should be familiar with how a Trie works. If not, please work on this problem: <a href="https://leetcode.com/problems/implement-trie-prefix-tree/">Implement Trie (Prefix Tree)</a> first.

Diff for: problems/add-binary/README.md

@@ -24,6 +24,9 @@
 <strong>Output:</strong> &quot;10101&quot;</pre>
 
 
+### Related Topics
+[[Math](https://github.com/openset/leetcode/tree/master/tag/math/README.md)] [[String](https://github.com/openset/leetcode/tree/master/tag/string/README.md)] 
+
 ### Similar Questions
   1. [Add Two Numbers](https://github.com/openset/leetcode/tree/master/problems/add-two-numbers) (Medium)
   1. [Multiply Strings](https://github.com/openset/leetcode/tree/master/problems/multiply-strings) (Medium)

Diff for: problems/add-digits/README.md

@@ -21,5 +21,14 @@
 <p><b>Follow up:</b><br />
 Could you do it without any loop/recursion in O(1) runtime?</p>
 
+### Related Topics
+[[Math](https://github.com/openset/leetcode/tree/master/tag/math/README.md)] 
+
 ### Similar Questions
   1. [Happy Number](https://github.com/openset/leetcode/tree/master/problems/happy-number) (Easy)
+
+### Hints
+  1. A naive implementation of the above process is trivial. Could you come up with other methods?
+  1. What are all the possible results?
+  1. How do they occur, periodically or randomly?
+  1. You may find this <a href="https://en.wikipedia.org/wiki/Digital_root" target="_blank">Wikipedia article</a> useful.

Diff for: problems/add-one-row-to-tree/README.md

@@ -68,4 +68,7 @@ A binary tree as following:
 <li>The given d is in range [1, maximum depth of the given tree + 1].</li>
 <li>The given binary tree has at least one tree node.</li>
 </ol>
-</p>
+</p>
+
+### Related Topics
+[[Tree](https://github.com/openset/leetcode/tree/master/tag/tree/README.md)] 

Diff for: problems/add-strings/README.md

@@ -18,6 +18,9 @@
 </ol>
 </p>
 
+### Related Topics
+[[Math](https://github.com/openset/leetcode/tree/master/tag/math/README.md)] 
+
 ### Similar Questions
   1. [Add Two Numbers](https://github.com/openset/leetcode/tree/master/problems/add-two-numbers) (Medium)
   1. [Multiply Strings](https://github.com/openset/leetcode/tree/master/problems/multiply-strings) (Medium)

Diff for: problems/add-two-numbers-ii/README.md

@@ -23,5 +23,8 @@ What if you cannot modify the input lists? In other words, reversing the lists i
 </pre>
 </p>
 
+### Related Topics
+[[Linked List](https://github.com/openset/leetcode/tree/master/tag/linked-list/README.md)] 
+
 ### Similar Questions
   1. [Add Two Numbers](https://github.com/openset/leetcode/tree/master/problems/add-two-numbers) (Medium)

Diff for: problems/add-two-numbers/README.md

@@ -20,6 +20,9 @@
 </pre>
 
 
+### Related Topics
+[[Linked List](https://github.com/openset/leetcode/tree/master/tag/linked-list/README.md)] [[Math](https://github.com/openset/leetcode/tree/master/tag/math/README.md)] 
+
 ### Similar Questions
   1. [Multiply Strings](https://github.com/openset/leetcode/tree/master/problems/multiply-strings) (Medium)
   1. [Add Binary](https://github.com/openset/leetcode/tree/master/problems/add-binary) (Easy)

Diff for: problems/additive-number/README.md

@@ -35,5 +35,8 @@
 <p><b>Follow up:</b><br />
 How would you handle overflow for very large input integers?</p>
 
+### Related Topics
+[[Backtracking](https://github.com/openset/leetcode/tree/master/tag/backtracking/README.md)] 
+
 ### Similar Questions
   1. [Split Array into Fibonacci Sequence](https://github.com/openset/leetcode/tree/master/problems/split-array-into-fibonacci-sequence) (Medium)

Diff for: problems/advantage-shuffle/README.md

@@ -40,3 +40,7 @@
 </ol>
 </div>
 </div>
+
+
+### Related Topics
+[[Greedy](https://github.com/openset/leetcode/tree/master/tag/greedy/README.md)] [[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)] 

Diff for: problems/all-nodes-distance-k-in-binary-tree/README.md

@@ -45,3 +45,7 @@ The descriptions of the inputs above are just serializations of these objects.
 	<li><code>0 &lt;= K &lt;= 1000</code>.</li>
 </ol>
 </div>
+
+
+### Related Topics
+[[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)] [[Breadth-first Search](https://github.com/openset/leetcode/tree/master/tag/breadth-first-search/README.md)] 

Diff for: problems/all-oone-data-structure/README.md

@@ -20,4 +20,7 @@
 
 <p>
 Challenge: Perform all these in O(1) time complexity.
-</p>
+</p>
+
+### Related Topics
+[[Design](https://github.com/openset/leetcode/tree/master/tag/design/README.md)] 

Diff for: problems/all-possible-full-binary-trees/README.md

@@ -33,3 +33,7 @@
 <ul>
 	<li><code>1 &lt;= N &lt;= 20</code></li>
 </ul>
+
+
+### Related Topics
+[[Tree](https://github.com/openset/leetcode/tree/master/tag/tree/README.md)] [[Recursion](https://github.com/openset/leetcode/tree/master/tag/recursion/README.md)] 

Diff for: problems/ambiguous-coordinates/README.md

@@ -51,3 +51,7 @@
 </ul>
 
 <p>&nbsp;</p>
+
+
+### Related Topics
+[[String](https://github.com/openset/leetcode/tree/master/tag/string/README.md)] 

Diff for: problems/arithmetic-slices-ii-subsequence/README.md

@@ -44,5 +44,8 @@ All arithmetic subsequence slices are:
 </pre>
 </p>
 
+### Related Topics
+[[Dynamic Programming](https://github.com/openset/leetcode/tree/master/tag/dynamic-programming/README.md)] 
+
 ### Similar Questions
   1. [Arithmetic Slices](https://github.com/openset/leetcode/tree/master/problems/arithmetic-slices) (Medium)

Diff for: problems/arithmetic-slices/README.md

@@ -32,5 +32,8 @@ A = [1, 2, 3, 4]
 return: 3, for 3 arithmetic slices in A: [1, 2, 3], [2, 3, 4] and [1, 2, 3, 4] itself.
 </pre>
 
+### Related Topics
+[[Math](https://github.com/openset/leetcode/tree/master/tag/math/README.md)] [[Dynamic Programming](https://github.com/openset/leetcode/tree/master/tag/dynamic-programming/README.md)] 
+
 ### Similar Questions
   1. [Arithmetic Slices II - Subsequence](https://github.com/openset/leetcode/tree/master/problems/arithmetic-slices-ii-subsequence) (Hard)

Diff for: problems/arranging-coins/README.md

@@ -38,4 +38,7 @@ The coins can form the following rows:
 
 Because the 4th row is incomplete, we return 3.
 </pre>
-</p>
+</p>
+
+### Related Topics
+[[Math](https://github.com/openset/leetcode/tree/master/tag/math/README.md)] [[Binary Search](https://github.com/openset/leetcode/tree/master/tag/binary-search/README.md)] 

Diff for: problems/array-nesting/README.md

@@ -31,6 +31,9 @@ S[0] = {A[0], A[5], A[6], A[2]} = {5, 6, 2, 0}
 </ol>
 </p>
 
+### Related Topics
+[[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)] 
+
 ### Similar Questions
   1. [Nested List Weight Sum](https://github.com/openset/leetcode/tree/master/problems/nested-list-weight-sum) (Easy)
   1. [Flatten Nested List Iterator](https://github.com/openset/leetcode/tree/master/problems/flatten-nested-list-iterator) (Medium)

Diff for: problems/array-of-doubled-pairs/README.md

@@ -66,3 +66,7 @@
 </div>
 </div>
 </div>
+
+
+### 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)] 

Diff for: problems/array-partition-i/README.md

@@ -25,4 +25,12 @@ Given an array of <b>2n</b> integers, your task is to group these integers into
 <li><b>n</b> is a positive integer, which is in the range of [1, 10000].</li>
 <li>All the integers in the array will be in the range of [-10000, 10000].</li>
 </ol>
-</p>
+</p>
+
+### Related Topics
+[[Array](https://github.com/openset/leetcode/tree/master/tag/array/README.md)] 
+### Hints
+  1. Obviously, brute force won't help here. Think of something else, take some example like 1,2,3,4.
+  1. How will you make pairs to get the result? There must be some pattern.
+  1. Did you observe that- Minimum element gets add into the result in sacrifice of maximum element.
+  1. Still won't able to find pairs? Sort the array and try to find the pattern.

Diff for: problems/assign-cookies/README.md

@@ -38,4 +38,7 @@ You need to output 1.
 You have 3 cookies and their sizes are big enough to gratify all of the children, 
 You need to output 2.
 </pre>
-</p>
+</p>
+
+### Related Topics
+[[Greedy](https://github.com/openset/leetcode/tree/master/tag/greedy/README.md)] 

Diff for: problems/asteroid-collision/README.md

@@ -61,5 +61,11 @@ Asteroids moving the same direction never meet, so no asteroids will meet each o
 <li>Each asteroid will be a non-zero integer in the range <code>[-1000, 1000].</code>.</li>
 </p>
 
+### Related Topics
+[[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)] 
+
 ### Similar Questions
   1. [Can Place Flowers](https://github.com/openset/leetcode/tree/master/problems/can-place-flowers) (Easy)
+
+### Hints
+  1. Say a row of asteroids is stable.  What happens when a new asteroid is added on the right?

Diff for: problems/average-of-levels-in-binary-tree/README.md

@@ -29,6 +29,9 @@ The average value of nodes on level 0 is 3,  on level 1 is 14.5, and on level 2
 </ol>
 </p>
 
+### Related Topics
+[[Tree](https://github.com/openset/leetcode/tree/master/tag/tree/README.md)] 
+
 ### Similar Questions
   1. [Binary Tree Level Order Traversal](https://github.com/openset/leetcode/tree/master/problems/binary-tree-level-order-traversal) (Medium)
   1. [Binary Tree Level Order Traversal II](https://github.com/openset/leetcode/tree/master/problems/binary-tree-level-order-traversal-ii) (Easy)

Diff for: problems/backspace-string-compare/README.md

@@ -62,3 +62,7 @@
 </div>
 </div>
 </div>
+
+
+### Related Topics
+[[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)] [[Two Pointers](https://github.com/openset/leetcode/tree/master/tag/two-pointers/README.md)] 

Diff for: problems/bag-of-tokens/README.md

@@ -59,3 +59,7 @@
 </div>
 </div>
 </div>
+
+
+### Related Topics
+[[Greedy](https://github.com/openset/leetcode/tree/master/tag/greedy/README.md)] 

Diff for: problems/balanced-binary-tree/README.md

@@ -45,5 +45,8 @@
 <p>Return false.</p>
 
 
+### Related Topics
+[[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)] 
+
 ### Similar Questions
   1. [Maximum Depth of Binary Tree](https://github.com/openset/leetcode/tree/master/problems/maximum-depth-of-binary-tree) (Easy)

Diff for: problems/baseball-game/README.md

@@ -61,4 +61,7 @@ Round 7: You could get 9 + 5 = 14 points. The sum is 27.
 <p><b>Note:</b><br />
 <li>The size of the input list will be between 1 and 1000.</li>
 <li>Every integer represented in the list will be between -30000 and 30000.</li>
-</p>
+</p>
+
+### Related Topics
+[[Stack](https://github.com/openset/leetcode/tree/master/tag/stack/README.md)] 

Diff for: problems/basic-calculator-ii/README.md

@@ -38,6 +38,9 @@
 	<li><b>Do not</b> use the <code>eval</code> built-in library function.</li>
 </ul>
 
+### Related Topics
+[[String](https://github.com/openset/leetcode/tree/master/tag/string/README.md)] 
+
 ### Similar Questions
   1. [Basic Calculator](https://github.com/openset/leetcode/tree/master/problems/basic-calculator) (Hard)
   1. [Expression Add Operators](https://github.com/openset/leetcode/tree/master/problems/expression-add-operators) (Hard)