// 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]

@@ -294,8 +294,67 @@
 / %5B2,3%5D%0A
+%0A/**%0A * @param %7Bnumber%5B%5D%7D nums%0A * @return %7Bnumber%5B%5D%7D%0A */%0A%0A%0A

add params