Combinations

Given two integers n and k, return all possible combinations of k numbers out of 1 2 3 ... n.

Make sure the combinations are sorted.

To elaborate,
1. Within every entry, elements should be sorted. [1, 4] is a valid entry while [4, 1] is not.
2. Entries should be sorted within themselves.

Example :
If n = 4 and k = 2, a solution is:

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

Warning : DO NOT USE LIBRARY FUNCTION FOR GENERATING COMBINATIONS.
Example : itertools.combinations in python.
If you do, we will disqualify your submission retroactively and give you penalty points.

Interview Code Editor
Hints
  • Solution Approach
  • Complete Solution
3049 successful submissions.
Asked In:
  • Amazon
  • Adobe
Click here to jump start your coding interview preparation