# [46. Permutations](https://leetcode.com/problems/permutations/)


## 题目

Given a collection of **distinct** integers, return all possible permutations.

**Example**:


    Input: [1,2,3]
    Output:
    [
      [1,2,3],
      [1,3,2],
      [2,1,3],
      [2,3,1],
      [3,1,2],
      [3,2,1]
    ]


## 题目大意

给定一个没有重复数字的序列，返回其所有可能的全排列。


## 解题思路

- 求出一个数组的排列组合中的所有排列，用 DFS 深搜即可。

## 代码

```go

package leetcode

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

func generatePermutation(nums []int, index int, p []int, res *[][]int, used *[]bool) {
	if index == len(nums) {
		temp := make([]int, len(p))
		copy(temp, p)
		*res = append(*res, temp)
		return
	}
	for i := 0; i < len(nums); i++ {
		if !(*used)[i] {
			(*used)[i] = true
			p = append(p, nums[i])
			generatePermutation(nums, index+1, p, res, used)
			p = p[:len(p)-1]
			(*used)[i] = false
		}
	}
	return
}

```