アルゴリズム_にぶんたんさく

package com.xwl;
/**
 *     
 * @author Administrator
 */
public class Test_erfenchazhao {
    public static void main(String[] args) {
        //      
        int[] arr = new int[] {12,13,25,64,87};
           System.out.println(search(arr, 12));
           System.out.println(search(arr, 13));
           System.out.println(search(arr, 25));
       }
       //                 key   
       public static int search(int[] arr, int key) {
           //       start
           int start = 0;
           //       end
           int end = arr.length - 1;
           //                    
           while (start <= end) {
               //     
               int middle = (start + end) / 2;
               //                key       -1   end
               if (key < arr[middle]) {
                   end = middle - 1;

               } else if (key > arr[middle]) {
                   //      =    +1
                   start = middle + 1;
               } else {
                   return middle;
               }
           }
           return -1;
       }
    }