递归－二分法查找
1.class BinarySearch { 2. public static void main(String[] args) { 3. int[] a = {2,3,4,5,6,7,8,9,10,13,17,18,24,56,78}; 4. System.out.println(search(a,5)); 5. } 6. 7. private static int search(int[] a, int key) { 8. return search(a,0,a.length,key); 9. } 10. 11. private static int search(int[] a, int from, int to, int key) { 12. if(from > to) return -1; 13. int middle = (from + to)/2; 14. if (a[middle] == key) return middle; 15. if (a[middle] > key) return search(a,from,middle-1,key); 16. else return search(a,middle+1,to,key); 17. } 18.}