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 #

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 #


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
}

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