384. Shuffle an Array

Posted 2020-08-16 鱼与海洋

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();

public class Solution {
    int[] originArray;
    int[] suffleArray;
    
    
    public Solution(int[] nums) {
        this.originArray = nums;
        this.suffleArray =  Arrays.copyOf(nums, nums.length); // Or nums.clone() 不能单纯取等号
    }
    
    /** Resets the array to its original configuration and return it. */
    public int[] reset() {
        return originArray;
    }
    
    /** Returns a random shuffling of the array. */
    public int[] shuffle() {
        for(int i = 0 ; i < suffleArray.length ; i++){
            int n = generateRandom();
            swap(i,n);
        }
        return suffleArray;
    }
    
    public void swap (int a, int b){
        int temp = suffleArray[a];
        suffleArray[a] = suffleArray[b];
        suffleArray[b] = temp;
    }
    
    public int generateRandom(){
        Random r = new Random();
        int n = r.nextInt(suffleArray.length);
        return n;
    }
}

/**
 * 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();
 */