[JoulinRouge]

I suggest you to read a book about algorithms. This one is pretty good: "Introduction to Algorithms" by Cormen and Rivest.

[andrewstuart2]

There is also a lot of great material on Coursera, MIT OpenCourseWare, etc. on algorithms.

[acomjean]

I second that, but would add data-structures to it. They go hand in hand. Being familiar with whats available will let you choose the correct one.

Using the right data structure and algorithm for the job can your code significantly faster.

[avinassh]

This was asked recently in Ask HN: https://news.ycombinator.com/item?id=8951241