Combinations

Given two integers n and k, return all possible combinations of k numbers chosen from the range [1, n].

You may return the answer in any order.

Example 1

Inputn = 4, k = 2

Output[[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]

All 2-number choices from the range [1, 4] are listed.

Example 2

Inputn = 1, k = 1

Output[[1]]

The only way to choose 1 number from [1, 1] is to choose 1.

Constraints