# [384.Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/)

## 题目

Given an integer array nums, design an algorithm to randomly shuffle the array. All permutations of the array should be equally likely as a result of the shuffling.

Implement the Solution class:

- Solution(int[] nums) Initializes the object with the integer array nums.
- int[] reset() Resets the array to its original configuration and returns it.
- int[] shuffle() Returns a random shuffling of the array.

**Example 1**:

    Input
    ["Solution", "shuffle", "reset", "shuffle"]
    [[[1, 2, 3]], [], [], []]
    Output
    [null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]

    Explanation
    Solution solution = new Solution([1, 2, 3]);
    solution.shuffle();    // Shuffle the array [1,2,3] and return its result.
    // Any permutation of [1,2,3] must be equally likely to be returned.
    // Example: return [3, 1, 2]
    solution.reset();      // Resets the array back to its original configuration [1,2,3]. Return [1, 2, 3]
    solution.shuffle();    // Returns the random shuffling of array [1,2,3]. Example: return [1, 3, 2]

**Constraints:**

- 1 <= nums.length <= 200
- -1000000 <= nums[i] <= 1000000
- All the elements of nums are unique.
- At most 5 * 10000 calls in total will be made to reset and shuffle.

## 题目大意

给你一个整数数组 nums ，设计算法来打乱一个没有重复元素的数组。

实现 Solution class:

- Solution(int[] nums) 使用整数数组 nums 初始化对象
- int[] reset() 重设数组到它的初始状态并返回
- int[] shuffle() 返回数组随机打乱后的结果

## 解题思路

- 使用 rand.Shuffle 进行数组随机打乱

## 代码

```go

package leetcode

import "math/rand"

type Solution struct {
	nums []int
}

func Constructor(nums []int) Solution {
	return Solution{
		nums: nums,
	}
}

/** Resets the array to its original configuration and return it. */
func (this *Solution) Reset() []int {
	return this.nums
}

/** Returns a random shuffling of the array. */
func (this *Solution) Shuffle() []int {
	arr := make([]int, len(this.nums))
	copy(arr, this.nums)
	rand.Shuffle(len(arr), func(i, j int) {
		arr[i], arr[j] = arr[j], arr[i]
	})
	return arr
}
```