Merge branch 'develop'
add an 8-queue solution
add a simple palindrome solution
快速排序：枢纽值「pivot」选取进行优化

https://github.com/xtaci/algorithms/issues/14
Merge pull request #22 from solome/patch-1

快速排序：枢纽值「pivot」选取进行优化
indent
Update sort_demo.cpp

added the head file for built-in function rand()
Merge pull request #23 from jackeylu/patch-1

Update sort_demo.cpp
Merge branch 'develop'
Merge branch 'master' of https://github.com/xtaci/algorithms
optimize astar alg, added verbose comments
Merge branch 'master' into develop