CMN=M!N!(M−N)!,(M=4, N=2)C_M^N =\frac{M!}{N!(M-N)!}, \text{(M=4, N=2)}

77. Combinations[E]

https://leetcode.com/problems/combinations/

Description

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

Example:

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

Solution

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class Solution:
    def combine(self, n: int, k: int) -> List[List[int]]:
        import itertools as it
        return [list(x) for x in list(it.combinations([i for i in range(1,n+1)], k))]