leetcode 384. Shuffle an Array | 384. 打乱数组（Fisher-Yates洗牌算法）

「爱情、让人受尽委屈。」 2022-08-30 15:51 120阅读 0赞

## 题目 ##

[https://leetcode.com/problems/shuffle-an-array/][https_leetcode.com_problems_shuffle-an-array]  
![在这里插入图片描述][a75581d33de0e3796be20f653e050848.png]

## 题解 ##

本代码参考了 JDK 源码 Collections.shuffle() 的实现，也可以看 [官方题解][Link 1]

class Solution { 
        int[] nums;
    
        public Solution(int[] nums) { 
            this.nums = nums;
        }
    
        /** * Resets the array to its original configuration and return it. */
        public int[] reset() { 
            return nums;
        }
    
        /** * Returns a random shuffling of the array. */
        public int[] shuffle() { 
            int[] arr = new int[nums.length];
            System.arraycopy(nums, 0, arr, 0, nums.length);
            // this is how Collections.shuffle() implements
            Random r = new Random();
            for (int i = arr.length; i > 1; i--)
                swap(arr, i - 1, r.nextInt(i));
            return arr;
        }
    
        public void swap(int[] arr, int i, int j) { 
            int t = arr[i];
            arr[i] = arr[j];
            arr[j] = t;
        }
    }
    
    /** * 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(); */

![在这里插入图片描述][2ce21bce1fade51bb0d6fdd27ea4a51d.png]

[https_leetcode.com_problems_shuffle-an-array]: https://leetcode.com/problems/shuffle-an-array/
[a75581d33de0e3796be20f653e050848.png]: /images/20220829/ff006ccd3d624f6ba853f40c14200aab.png
[Link 1]: https://leetcode.com/problems/shuffle-an-array/solution/
[2ce21bce1fade51bb0d6fdd27ea4a51d.png]: /images/20220829/622402c946954fd98e0638df4cc9b25c.png