题目：

题解：

func permute(nums []int) [][]int {
	var (
		n   = len(nums)
		dfs func(vals []int) // 已选择数 排列为vals 后续回溯继续选择 直至选完
		ans [][]int
	)

	dfs = func(vals []int) {
		//边界
		if len(vals) == n {
			ans = append(ans, vals)
		}
		//转移 枚举选哪个
		for _, x := range nums {
			if !slices.Contains(vals, x) { // 不包含才能选
				var valsTmp = make([]int, len(vals))
				copy(valsTmp, vals)
				valsTmp = append(valsTmp, x) // 选

				dfs(valsTmp)
			}
		}
	}
	dfs([]int{})

	return ans
}