TwoSumSortBinarySearch.java

private boolean sumsToTarget(int[] arr, int k) { 
   Arrays.sort(arr); 
   for (int i = 0; i < arr.length; i++) { 
     int siblingIndex = Arrays.binarySearch(arr, k - A[i]); 
     if (siblingIndex >= 0) { 
        // Found it! 
        if (siblingIndex != i || (i > 0 && arr[i-1] == arr[i]) || (i < arr.length - 1 && arr[i+1] == arr[i])) 
          { return true; } 
     } 
   } 
   return false; 
}