Leon's Blog

Matrix Rotation Question Given a NxN matrix, where each element in the matrix is integer, write a method to rotate the matrix by 90 degrees. Answer We can separate the question to a set of small questions. The matrix could be considered as N/2 layers, which is a circle from...

KMP algorithm String search algorithm When you have a string “abacaabacabacabaabb”, we call it target string(T). Then there is another string “abacab” named matching string(M). How to figure out the start index in T which match M? If we look into it, we could find that if start from the...

Find fun in algorithm (In Java) Preface Algorithm always be boring and hard to be understood, I didn’t learn it very well in college. After graduated, I spend much of my time on programming language, such as C, Java, Javasript etc. But after worked for several years, I noticed that...

Download the resources you needed Go to http://rubyinstaller.org/downloads/ download ruby for using gem in cmd, you need download two packages: Ruby 2.2.2 (x64) DevKit-mingw64-64-4.7.2-20130224-1432-sfx.exe Extract devkit to a directory, go into it and execute ruby dk.rb init, then open config.yml and add the home of ruby at the bottom, like...