java实现二分查找

java实现二分查找

package search;public class BinarySearch {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubint arr[] = {3,6,8,10,12,15,16,18,21,25,30};int test = binarySearch(arr,30);System.out.println(test);}/* * @param arr 有序数组 * @param des 要查找的数 * @return 查找的下角标  */public static int binarySearch(int arr[],int des){int low = 0;int high = arr.length-1;int middle = (low+high)/2;while(low<=high){if(arr[middle]==des){System.out.println("刚好中间，找到了！");return middle;}else if(des < arr[middle]){high = middle-1;middle=(low+high)/2;}else if(des > arr[middle]){low = middle+1;middle=(low+high)/2;}}return -1;}}