Sort&Search:
3Sum
3SumCloset
4Sum
sort colors
search for a range
search in a rotated sorted array I && II
search insert position
sqrt(x)
first missing positive 
Merge Sorted Array
Search a 2D Matrix
Two Sum




Linkedlist:
merge two sorted lists
add two numbers
Partition List
Remove Duplicates from Sorted List I,II
Remove Nth Node From End of List
Reverse Linked List II
Reverse Nodes in k-Group
Rotate List
Swap Nodes in Pairs




String manipulation:
add binary
anagrams
Length of Last Word
Longest Common Prefix
Longest Palindromic Substring
Longest Substring Without Repeating Characters
Substring with Concatenation of All Words




Tree:
balanced binary tree
binary tree inorder traversal
binary tree level order traversal I,II
binary tree maximum path sum
binary tree zigzag level order traversal
construct binary tree from inorder and postorder traversal
construct binary tree from preorder and inorder traversal
convert sorted array to binary search tree
convert sorted list to binary search tree
flatten binary tree to linked list
Maximum Depth of Binary Tree
Minimum Depth of Binary Tree
Populating Next Right Pointers in Each Node I,II
Recover Binary Search Tree
Same Tree
Symmetric Tree
Unique Binary Search Trees I,II
Validate Binary Search Tree









Dynamic programming:
climbing stairs
combination sum I,II
combinations
decode ways
edit distance
generate parentheses
Interleaving String
Letter Combinations of a Phone Number
Minimum Path Sum
Permutations
Unique Paths I,II


Recursion:
N-Queens I,II
Path Sum I,II
Pow(x, n)
Subsets I,II
Sudoku Solver
Word Search    -dfs




Miscellaneous:
best time to buy and sell stock I,II,III
container with most water
count and say
gray code
Insert Interval
jump game I,II
Maximal Rectangle
Maximum Subarray 
Median of Two Sorted Arrays
Merge Intervals
Minimum Window Substring
Multiply Strings
Palindrome Number
Pascal's Triangle I,II
Plus One
Remove Duplicates from Sorted Array I,II
Restore IP Addresses
Reverse Integer
Rotate Image
Set Matrix Zeroes
Spiral Matrix I,II
Trapping Rain Water
Valid Sudoku








Heap:
Merge k Sorted Lists



Stack:
Largest Rectangle in Histogram
Longest Valid Parentheses
Valid Parentheses




Not done yet:
distinct subsequence
divide two integers
implementing strStr()
Integer to Roman
Next Permutation
Permutation Sequence
Permutations II
Regular Expression Matching
Remove Element
Roman to Integer
Scramble String
Simplify Path
String to Integer (atoi)
Text Justification
Triangle
Valid Number
Wildcard Matching
ZigZag Conversion