润X：第一题 兑换硬币 q = int(input()) a=0 while a<q:     b,n= input().split(" ")     b=int(b)     n=int(n)     r = input()     lst = r.split(" ")     lst = [int(lst[i]) for i in range(b)]     num = [0 for i in range(n+1)]     num[0] = 1     for i in range(b):         for j in range(1, n+1):             if j >= lst[i]:                 num[j] += num[j-lst[i]]     print(num[n])     a=a+1