Add: Navigation

Author: openset

problems/graph-valid-tree/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/single-number-iii "Single Number III")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/trips-and-users "Trips and Users")
+
 ## 261. Graph Valid Tree (Medium)
 
 

problems/group-anagrams/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/rotate-image "Rotate Image")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/powx-n "Pow(x, n)")
+
 ## 49. Group Anagrams (Medium)
 
 <p>Given an array of strings, group anagrams together.</p>

problems/group-shifted-strings/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/strobogrammatic-number-iii "Strobogrammatic Number III")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/count-univalue-subtrees "Count Univalue Subtrees")
+
 ## 249. Group Shifted Strings (Medium)
 
 

problems/guess-number-higher-or-lower-ii/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/guess-number-higher-or-lower "Guess Number Higher or Lower")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/wiggle-subsequence "Wiggle Subsequence")
+
 ## 375. Guess Number Higher or Lower II (Medium)
 
 <p>We are playing the Guess Game. The game is as follows:</p>

problems/guess-number-higher-or-lower/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/find-k-pairs-with-smallest-sums "Find K Pairs with Smallest Sums")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/guess-number-higher-or-lower-ii "Guess Number Higher or Lower II")
+
 ## 374. Guess Number Higher or Lower (Easy)
 
 <p>We are playing the Guess Game. The game is as follows:</p>

problems/hamming-distance/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/lfu-cache "LFU Cache")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/minimum-moves-to-equal-array-elements-ii "Minimum Moves to Equal Array Elements II")
+
 ## 461. Hamming Distance (Easy)
 
 <p>The <a href="https://en.wikipedia.org/wiki/Hamming_distance" target="_blank">Hamming distance</a> between two integers is the number of positions at which the corresponding bits are different.</p>

problems/happy-number/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/bitwise-and-of-numbers-range "Bitwise AND of Numbers Range")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/remove-linked-list-elements "Remove Linked List Elements")
+
 ## 202. Happy Number (Easy)
 
 <p>Write an algorithm to determine if a number is &quot;happy&quot;.</p>

problems/heaters/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/ones-and-zeroes "Ones and Zeroes")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/number-complement "Number Complement")
+
 ## 475. Heaters (Easy)
 
 <p>Winter is coming! Your first job during the contest is to design a standard heater with fixed warm radius to warm all the houses.</p>

problems/house-robber-iii/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/palindrome-pairs "Palindrome Pairs")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/counting-bits "Counting Bits")
+
 ## 337. House Robber III (Medium)
 
 <p>The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the &quot;root.&quot; Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that &quot;all houses in this place forms a binary tree&quot;. It will automatically contact the police if two directly-linked houses were broken into on the same night.</p>

problems/house-robber/README.md

@@ -5,6 +5,10 @@
 <!--|@home      https://github.com/openset/leetcode                        |-->
 <!--+----------------------------------------------------------------------+-->
 
+[< Previous](https://github.com/openset/leetcode/tree/master/problems/rising-temperature "Rising Temperature")
+　　　　　　　　　　　　　　　　
+[Next >](https://github.com/openset/leetcode/tree/master/problems/binary-tree-right-side-view "Binary Tree Right Side View")
+
 ## 198. House Robber (Easy)
 
 <p>You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and <b>it will automatically contact the police if two adjacent houses were broken into on the same night</b>.</p>