Practice on existing problems. Check out https://www.hackerrank.com/ https://www.hackerrank.com/ and https://code.google.com/codejam https://code.google.com/cod

Practice on existing problems. Check out https://www.hackerrank.com/ https://www.hackerrank.com/ and https://code.google.com/codejam https://code.google.com/codejam. I particularly like Google Code Jam because they provide an analysis on how to approach these kinds of algorithm exercises.