设有一个背包可以放入物品的重量为s，现有n件物品，重量分别为w[0],w[1],...,[n-1]。问题是能否从这n件物品中选择若干件放入此背包中使得放入的重量之和正好等于s。-Has a backpack can be placed in the weights of the articles of s, the existing n items, weight W [0], w [1], ..., [n-1]. The question is whether this certain wei