In the paper, contraction of a dynamic vector (i.e., both the number and the individuals of elements in the vector are non-deterministic) in a tensor is programmed. It accumulates complete N-combinations of one element of every M-set by recursion algorithm for object-oriented programming. Here, N is dynamic, i.e., uncertain before user's programming. This algorithm has overcome the difficulty of writing loop sentences in uncertain arity, yet the complexity of computation is exponential. So a quantum algorithm is proposed for realizing the computation in an acceptable time.