五分钟前刚结束的电面，自己刷题还是太少了，写的很不好T^T
given a list of positive integers, not necessarily distinct.
Write a function that tells whether any sub-list of integers add up to a particular target value.
for example:
{1, 3 ,5, 11},
target = 2 -> False
target = 6 -> True
target = 7 -> False