Question
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();
Solution
TODO
Code
import java.util.Random;
public class Solution {
private int[] nums;
private Random random;
public Solution(int[] nums) {
this.nums = nums;
random = new Random();
}
/** 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() {
if(nums == null) return null;
int [] a = nums.clone();
for(int i=0; i<a.length; i++) {
int j = random.nextInt(i+1);
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
return a;
}
}
Performance
TODO