g0301_0400.s0384_shuffle_an_array.Solution Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java Show documentation

Java-based LeetCode algorithm problem solutions, regularly updated

There is a newer version: 1.37

package g0301_0400.s0384_shuffle_an_array;

// #Medium #Top_Interview_Questions #Array #Math #Randomized

import java.security.SecureRandom;

public class Solution {
    private int[] nums;
    private SecureRandom random;

    public Solution(int[] nums) {
        this.nums = nums;
        this.random = new SecureRandom();
    }

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

    // Returns a random shuffling of the array.
    public int[] shuffle() {
        int[] shuffled = this.nums.clone();
        for (int i = nums.length - 1; i > 0; i--) {
            int j = random.nextInt(i + 1);
            swap(shuffled, i, j);
        }
        return shuffled;
    }

    private void swap(int[] shuffled, int i, int j) {
        int tmp = shuffled[i];
        shuffled[i] = shuffled[j];
        shuffled[j] = tmp;
    }
}