// Given an array of integers, 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.

// Find all the elements that appear twice in this array.

// Could you do it without extra space and in O(n) runtime?

// Example:
// Input:
// [4,3,2,7,8,2,3,1]

// Output:
// [2,3]

// Given an array of integers, 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.

// Find all the elements that appear twice in this array.

// Could you do it without extra space and in O(n) runtime?

// Example:
// Input:
// [4,3,2,7,8,2,3,1]

// Output:
// [2,3]

/**
 * @param {number[]} nums
 * @return {number[]}
 */



add params