0077. Combinations

#77. Combinations

Topics

• Array
• Backtracking

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

You may return the answer in any order.

Example 1:

    Input: n = 4, k = 2
    Output:
    [
    [2,4],
    [3,4],
    [2,3],
    [1,2],
    [1,3],
    [1,4],
    ]

Example 2:

    Input: n = 1, k = 1
    Output: [[1]]

Constraints:

• 1 <= n <= 20
• 1 <= k <= n