[Modify] modify the algorithms to add edges of existing nodes
[Fix] Hot fix
Merge branch 'master' of https://github.com/ryaninhust/sampling
[Modify] modify ff to add edges to existing nodes
Merge pull request #11 from Hyiiego/master

[Modify] modify the algorithms to add edges of existing nodes
Merge branch 'master' of https://github.com/ryaninhust/sampling
[Add] add algorithm which choose the node with largest degree to query
Merge pull request #13 from Hyiiego/master

degree_largest
[Fix] fix bug in update graph
Merge pull request #14 from Hyiiego/master

[Fix] fix bug in update graph
Merge branch 'master' of https://github.com/ryaninhust/sampling
Add attribute