Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.
1 <= nums.length <= 6, -10 <= nums[i] <= 10, All integers of nums are unique
Backtracking: build permutation by adding unused elements one by one, backtrack after exploring each choice.
def permute(nums):
result = []
def backtrack(path, remaining):
if not remaining:
result.append(path)
return
for i in range(len(remaining)):
backtrack(path + [remaining[i]], remaining[:i] + remaining[i+1:])
backtrack([], nums)
return result