func permute(nums []int) [][]int {
	if len(nums) == 0 {
		return nil
	}
	used, cur, res := make([]bool, len(nums)), []int{}, [][]int{}

	generatePermutation(&nums, &res, &used, cur)
	return res
}

func generatePermutation(nums *[]int, res *[][]int, used *[]bool, cur []int) {

	if len(*nums) == len(cur) {
		//just for test
		fmt.Printf("添加元素------>")
		for _, val := range cur {
			fmt.Printf("%v\t", val)
		}
		fmt.Println(cur)
		temp := make([]int, len(*nums))
		copy(temp, cur)
		*res = append(*res, temp)
		//fmt.Println(res)
	}

	//添加正确之后的对比
	//if len(*nums) == len(cur) {
	//	ans := make([]int, len(cur))
	//	copy(ans, cur)
	//	*res = append(*res, ans)
	//	return
	//}

	for i := 0; i < len(*nums); i++ {
		//如果当前值没有使用
		if !(*used)[i] {
			(*used)[i] = true
			cur = append(cur, (*nums)[i])
			//进行递归
			generatePermutation(nums, res, used, cur)
			//到这里说明之前的已经遍历完了
			(*used)[i] = false
			cur = cur[:len(cur)-1]
		}
	}

}