LeetCode384. Shuffle an Array

最新推荐文章于 2025-06-14 18:42:24 发布

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最新推荐文章于 2025-06-14 18:42:24 发布

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分类专栏： leetcode 文章标签： leetcode numbers

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本文介绍了一个使用经典洗牌算法实现数组随机排列的例子。通过构造一个包含特定整数的数组，并利用Java内置的Random类实现数组元素的位置交换，达到了对数组进行随机重排的目的。文章还提供了重置数组至初始状态的方法。

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题目要求:
Shuffle a set of numbers without duplicates.

Example:

// Init an array with set 1, 2, and 3.
int[] nums = {1,2,3};
Solution solution = new Solution(nums);

// Shuffle the array [1,2,3] and return its result. Any permutation of [1,2,3] must equally likely to be returned.
solution.shuffle();

// Resets the array back to its original configuration [1,2,3].
solution.reset();

// Returns the random shuffling of array [1,2,3].
solution.shuffle();

使用经典的洗牌算法,同时注意java中的random.nextint()中范围的问题

public class Solution {
    private int[] numsRef;
    private int[] nums;
    public Solution(int[] nums) {
        numsRef = Arrays.copyOf(nums, nums.length);
        this.nums = nums;
    }

    /** Resets the array to its original configuration and return it. */
    public int[] reset() {
        return numsRef;
    }

    /** Returns a random shuffling of the array. */
    public int[] shuffle() {
        //使用经典的洗牌算法处理
        if(nums == null) return null;
        int length = nums.length;
        for(int i = length - 1; i >= 0; i--) {
            Random ranx = new Random();
            int index = ranx.nextInt(i + 1);
            int temple = nums[i];
            nums[i] = nums[index];
            nums[index] = temple;
        }
        return nums;

    }
}


/**
 * Your Solution object will be instantiated and called as such:
 * Solution obj = new Solution(nums);
 * int[] param_1 = obj.reset();
 * int[] param_2 = obj.shuffle();
 */