0384. Shuffle an Array

# 384.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 #

• 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 #

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
}

Apr 8, 2023