### 216. Combination Sum III

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers.

Example 1:

Input: k = 3, n = 7

Output:

[[1,2,4]]


Example 2:

Input: k = 3, n = 9

Output:

[[1,2,6], [1,3,5], [2,3,4]]


Credits:
Special thanks to @mithmatt for adding this problem and creating all test cases.

Seen this question in a real interview before?
When did you encounter this question?
Which company?