5.二分查找

public class BinarySearch {
    //二分查找
    public static void search(int[] arr,int target){
        int left=0;
        int right=arr.length-1;
        int mid=0;
        while (left<=right){
            mid=left+(right-left)/2;
            if(arr[mid]==target)break;
            else if(arr[mid]>target)right=mid-1;
            else left=mid+1;
        }
        System.out.println(arr[mid]);
    }

    public static void main(String[] args) {
        int[] arr=new int[]{1,2,3,4,5,6,7,8,9};
        search(arr,2);
    }
}