Medium

Quiz

#77 Combinations

APPROACH

Return all possible size-k combinations of integers drawn from the range [1, n]. Results may be in any order.

Example 1:

Input: n = 4, k = 2

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

Explanation: There are 4 choose 2 = 6 total combinations.

Note that combinations are unordered, i.e., [1,2] and [2,1] are considered to be the same combination.

Example 2:

Input: n = 1, k = 1

Output: [[1]]

Explanation: There is 1 choose 1 = 1 total combination.

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What is the optimal approach for this problem?