求解背包问题：一个背包可装总重量 T，现有 n 个物件，其重量分别为（W1、W2、…、Wn）。问能否从这 n 个物件中挑选若干个物件放入背包中，使其总重量正好为 T ？若有解则给出全部解，否则输出无解-Knapsack problem: a backpack can be fitted to the total weight of T n existing object, its weight (W1, W2, ..., Wn). Asked whether this n objects to the selection of a number of objects into the backpack, so that the total weight of opportunity for T? If the solution is given in the full solution, otherwise output no solution