This folder contains some interesting algorithmic problems and my solutions. Leetcode OJ URL: http://leetcode.com/onlinejudge
Currently solved: 67
| Problem (alphabetical) | Difficulty | Frequency | Notes |
|---|---|---|---|
| 3sum | 3 | 5 | array, two pointers |
| AddBinary | 2 | 4 | string, two pointers, math |
| AddTwoNumbers | 3 | 4 | linkedlist, two pointers |
| Anagrams | 3 | 4 | string, hashtable |
| Balanced Binary Tree | 1 | 2 | tree, recursion |
| BS in-order traveral | 4 | 3 | stack, hashtable |
| BS level-order trav | 3 | 4 | queue, hashtable |
| BS zigzag trav | 4 | 3 | queue, hashtable |
| BinaryTreeMaxPathSum | 4 | 2 | tree, dfs |
| Decode ways | 4 | 4 | dp |
| Divide two int | 4 | 3 | math |
| Flatten BS to list | 3 | 3 | recursion |
| Convert array to BST | 2 | 3 | recursion, divide and conquer |
| Convert list to BST | 4 | 3 | Linked list, recursion |
| Climbing Stairs | 2 | 5 | dp |
| Combinations | 3 | 4 | combinations |
| Combination Sum | 3 | 3 | array, combinations |
| Inorder&preorder | 3 | 3 | recursion, tree |
| Inorder&postorder | 3 | 3 | recursion, tree |
| Generate paren | 4 | 4 | dp |
| GrayCode | 4 | 2 | combination, math |
| Insert Interval | 4 | 5 | red-black tree, array |
| Int2Roman | 3 | 4 | math |
| LetterComb Phone book | 3 | 3 | combination, recursion |
| LongestSubstringWoRep | 3 | 2 | string, hashtable, two ptrs |
| MaxDepthOfBinaryTree | 1 | 1 | tree |
| MergeInterval | 4 | 5 | merge, arraylist |
| Merge K sorted list | 3 | 4 | heap, linked list |
| MergeSortedArray | 2 | 5 | array |
| MergeTwoSortedList | 2 | 5 | linkedlist, merge |
| MinDepthOfBinaryTree | 1 | 1 | tree |
| Multiply strings | 4 | 3 | math, array, string |
| PalindromeNumber | 2 | 2 | math |
| Palindrome Partition | 5 | 3 | recursion |
| Partition list | 3 | 3 | Linked list |
| PathSum | 1 | 3 | tree, dfs |
| PathSum II | 2 | 2 | tree, dfs |
| Permutation | 3 | 4 | recursion, array |
| PlusOne | 2 | 2 | Math |
| Pow | 3 | 5 | binary search, math |
| Recover BST | 5 | 4 | BST, traveral |
| RemDupFrmSortedArray | 1 | 3 | Array |
| RemDupfromsortedArray2 | 2 | 3 | Array |
| RemDupfrmSortedlst | 2 | 3 | Linked list |
| RemDupfrmSortedLst2 | 3 | 3 | Linked List |
| Remove element | 1 | 4 | two pointers |
| Rm N from end | 2 | 3 | two pointers |
| Reverse Integer | 2 | 3 | math |
| Roman2Int | 2 | 4 | math |
| Rotated array search | 3 | 3 | binary search |
| Search for a range | 4 | 3 | Array, binary search |
| Set Matrix Zeroes | 2 | 5 | 2-D array |
| StrStr() | 4 | 5 | string, KMP |
| Subsets | 3 | 4 | recursion, combinations |
| String to Integer | 2 | 5 | string, math |
| SumRoot2LeafNumbers | 2 | 4 | tree, dfs |
| Swap nodes in pairs | 2 | 4 | linked list |
| ValidPalindrome | 2 | 5 | array, two pointers |
| ValidateParenthesis | 2 | 5 | stack |
| ValidateBST | 3 | 5 | tree, dfs |
| Word Ladder | 4 | 5 | tree, bfs |
| Word search | 4 | 4 | tree, dfs |
| SameTree | 1 | 1 | tree, dfs |
| Sqrt | 4 | 4 | binary search |
| SymmtricTree | 1 | 2 | tree, dfs |
| ThreeSumClosest | 3 | 1 | array, two pointers |
| TwoSum | 2 | 5 | array, set, sort, two ptrs |
