public int binarySearch(int[] nums, int target) {

         int low = 0;

         int high = nums.length;

         while (low <= high) {

             int mid = (low + high) / 2;

             if (nums[mid] == target)

                 return mid;

             else if (nums[mid] < target)

                 low = mid + 1;

             else

                 high = mid - 1;

         }

         return -1;

     }