说明：  ACM常用模板，对于搞ACM竞赛的同学有很大的帮助，上面整理了数论、图论、组合数学、计算几何等大部分算法和源码。
(ACM commonly used templates, ACM contest for students engaged in a great help, finishing above the number theory, graph theory, combinatorial mathematics, computational geometry, and most other algorithms and source code.)