Given two arrays, write a function to compute their intersection.
 Example:
 Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].
 Note:
 Each element in the result must be unique.
 The result can be in any order. 

/**
 * Return an array of size *returnSize.
 * Note: The returned array must be malloced, assume caller calls free().
 */

int compare (const void * a, const void * b)
{
  return ( *(int*)a - *(int*)b );
}

int* intersection(int* nums1, int nums1Size, int* nums2, int nums2Size, int* returnSize)
{
    if(NULL == nums1 || NULL==nums2)
        return NULL;
    
    int cnt = 0;
    *returnSize =(nums1Size > nums2Size) ? nums2Size:nums1Size;
    int *res =(int *)malloc(*returnSize * sizeof(int));
    
    /*sort nums1 nums2*/
    qsort (nums1, nums1Size, sizeof(int), compare);
    qsort (nums2, nums2Size, sizeof(int), compare);
    
    for(int i = 0;i < nums1Size;i++ )
    {
        /*nums1 element found in nums2*/
        if(bsearch (&nums1[i], nums2, nums2Size, sizeof (int), compare) != NULL)
        {
            /*common element is not in res,add it,the res length is cnt*/
            if(NULL == bsearch (&nums1[i], res, cnt, sizeof (int), compare))
                res[cnt++] = nums1[i];
        }
    }
    
    *returnSize = cnt;
    return res;
    
    
   
}