add comments
very concise and smart solution
Update
cur<= pre only add pre; else add (cur- pre)
Update by 9/16
update on 9/17/2014
update on 9/16
Recursion
update on 9/21
update on Sep 22
9/23/2014 DFS
Sep 23
9/23
9/23 DFS&Combinations
9/24 DFS
9/24 DFS
9/24
9/24
9/26 Binary Search
9/26 Array (Merge two sorted array...etc)