[Day41]-[回溯]- 全排列

输入：nums = [1,2,3]输出：[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]

输入：nums = [0,1]输出：[[0,1],[1,0]]

输入：nums = [1]输出：[[1]]

func TestPermute(t *testing.T) {	var res [][]int	var permute func(nums []int) [][]int	var backTrack func(nums []int, track []int)	var isSet func(trace []int, target int) bool	isSet = func(trace []int, target int) bool {		for _, val := range trace {			if target == val {				return true			}		}		return false
	}	backTrack = func(nums []int, track []int) {		if len(track) == len(nums) {			res = append(res, append([]int{}, track...))			return		}		for i := 0; i < len(nums); i++ {			if false == isSet(track, nums[i]) {				track = append(track, nums[i])				backTrack(nums, track)				track = track[:len(track)-1]			}		}	}	permute = func(nums []int) [][]int {		backTrack(nums, []int{})		return res	}	permute([]int{1, 2, 3})	t.Log(res)}