多边形游戏，属于国际信息学奥林匹克竞赛试题。单人进行，开始时有一个或n个顶点构成的多边形，每个顶点被赋初始值，每条边有运算符号+、X。按步进行-Polygon game, belongs to the international informatics Olympic competition for the test. There is a single, start a vertex constitute or n polygon, each vertices are an initial v