[cpcarey]

LeetCode has a great collection of problems that you can practice with and test your solution in the browser (https://oj.leetcode.com/). The discussion sections were helpful as well.

GeeksforGeeks also has a collection of problems and analyses (http://geeksforgeeks.org/fundamentals-of-algorithms/).

So after refreshing yourself on the fundamentals, practice, practice, practice. Hope this helps!