make Python2/Python3 compatible

update topological sorting

add CNAME

fix lintcode crawler

update contribution

Merge pull request billryan#112 from SmartJuneThx/patch-1

关于题解一源码分析的`i >= right`条件

update knapsack

Merge pull request billryan#109 from Lisanaaa/master

Update gcd.md

simplify readme

simplify GitHub readme page