K Sum问题求解

Two Sum: http://www.cnblogs.com/ganganloveu/p/3728849.html

Three Sum:http://www.cnblogs.com/-wang-cheng/p/4856282.html
改进的：https://my.oschina.net/yumifan/blog/225511

快速排序：http://blog.csdn.net/morewindows/article/details/6684558

K sum: http://www.sigmainfy.com/blog/summary-of-ksum-problems.html