对背包问题进行的求解，能够处理体积相同，但是不同物品的问题-The solution on the knapsack problem that can handle the same volume, but the problem of different items

创建三个结构体，分别表示圆形、圆柱、圆锥，计算圆柱体、圆锥的体积-Create three structural body, respectively, said circular, cylindrical, cone, the calculated cylinder, cone volume