二分查找

package com.sxc.search;

import org.junit.Test;

public class BinarySearch {
    public  static int[] array = {1,3,5,7,9,15,13,12,10};//待搜索数组
    public static int search = 9;//待查找数字
    public int getIndex(int begin, int end) {

        int middle = begin + (end - begin)/2;
        if (array[middle] == search){
            return middle;
        }else if (end <= begin){
            return -1;
        }
        else {
            int lertResult = getIndex(begin, middle - 1);
            if (lertResult != -1) {//递归结束条件
                return lertResult;
            } else {
                int rightResult = getIndex(middle + 1, end);//递归实现
                if (rightResult != -1) {
                    return rightResult;
                } else {
                    return -1;
                }
            }
        }
    }
    @Test
    public void test2(){//测试示例
        BinarySearch m = new BinarySearch();
        int result = m.getIndex(0, array.length-1);
        System.out.println(result);//输出9的下标
    }
}