46_Permutations.md

46. Permutations

Given a collection of distinct integers, return all possible permutations.

Example:

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

def permute(self, nums: List[int]) -> List[List[int]]:
        result = []
        if len(nums) ==0: return result

        def gen_pattern(build, index):
            if len(nums) == index:
                result.append(build)
                return
            
            for num in nums:
                if not num in build: 
                    gen_pattern(build+[num], index+1)
        
        gen_pattern([], 0)
        return result

Runtime: 36 ms, faster than 86.09% of Python3 online submissions for Permutations.
Memory Usage: 14.3 MB, less than 100.00% of Python3 online submissions for Permutations.