问题陈述：给定N个数，和一个数T，判定是否可以从N个数中取出若干个数，使它们的和等于T。输出：YES或者NO。把N个数看成一个集合，问题就是从这个集合中选出一个子集，使这个子集满足和是T-Problem Statement: a given number N, and a number of T, and determines whether or not can be removed from the number N of a certain number, so that their eq