```
class Solution:
def twoSum(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: List[int]
"""
ordered_nums = list(enumerate(nums))
ordered_nums.sort(key=lambda x: x[1])
while len(ordered_nums) >= 2:
lhs = ordered_nums[0]
for rhs in ordered_nums[1:]:
if lhs[1] + rhs[1] == target:
return [lhs[0], rhs[0]]
del ordered_nums[0]
return None
```