Binary Tree Array Search

This version returns the index of the goal, or -1 if not found.

public static int search (String [] arr, int low,
                   int high, String goal) {
  if ( high < low )
     return -1;       // goal not found
    else
     { int root = (low + high) / 2;
       int test = goal.compareTo(arr[root]);
       if ( test == 0 )
          return root;     // found
         else if ( test < 0 )
                 return search(arr, low,
                               root - 1, goal);
            else return search(arr, root + 1,
                               high, goal); } }

This binary search uses divide-and-conquer and takes O(log(n)) time.