```
class Solution(object):
def combinationSum4(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: int
"""
maps = {i: 0 for i in range(target + 1)}
maps[0] = 1
i = 1
while i <= target:
for num in nums:
if num <= i:
maps[i] += maps[i - num]
i += 1
return maps[target]
```