leetcode 刷题 46 47

class Solution:
    def permute(self, nums: List[int]) -> List[List[int]]:
        ans = [nums]
        for i in range(1, len(nums)):
            m = len(ans)
            for k in range(m):
                for j in range(i):
                    ans.append(ans[k][:])
                    ans[-1][j], ans[-1][i] = ans[-1][i], ans[-1][j]
        return ans

class Solution:
    def permuteUnique(self, nums: List[int]) -> List[List[int]]:
        ans = [nums]
        for i in range(1, len(nums)):
            m = len(ans)
            for k in range(m):
                for j in range(i - 1, -1, -1):
                    if ans[k][j] == ans[k][i]:
                        break
                    ans.append(ans[k][:])
                    val = ans[-1][j]
                    ans[-1][j] = ans[-1][i]
                    ans[-1][i] = val
        return ans