已知N种物品和一个容纳重量为M的背包，每种物品均有自己的重量和效益值，假设这N种物品的重量和有可能大于M，这种情况下，选择哪种物品装入背包能获得最大效益值-Are known to have n kinds of goods and a weight capacity of M, backpacks, each item has its own weight and efficiency values, assume that n kinds of goods may be greater th