permutations.py

class Solution(object):
    def permute(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        result = []
        temp = []
        self.backtracking(result, temp, nums)
        return result
        
    def backtracking(self, result, temp, nums):
        if len(temp) == len(nums):
            result.append(temp[:])
            return
        for i in range(0, len(nums)):
            if nums[i] in temp: continue
            temp.append(nums[i])
            self.backtracking(result, temp, nums)
            temp.pop()