Merge pull request #8 from xmuliang/master

add heap sort
using TAB instead of space in heap_sort.h
Update heap_sort.h
Update README.md
Merge pull request #9 from xmuliang/master

add kruskal minimum spanning tree algorithm
update Makefile, pretty the kruskal_mst.h
update readme.md
Merge pull request #1 from xtaci/master

merge1