#17.有四個數字:1 2 3 4 ,能組成多少個各不相同且數字不重複的三位數?各是多少? count = 0 for i in range(1,5): for j in range(1,5): for k in range(1,5): if i == j or j == k or i == k: continue #來到循環開始的地方:for i in range(1,5) count += 1 print(str(i)+str(j)+str(k)) print(count)