二分查询

package lwr;

public class recursionBinarySearch {

    public static int recursionBinarySearch(int[] arr,int key,int low,int high){
        if(key>arr[high]||key<arr[low]||low>high){
            return -1;
        }
        int middle = (low+high)/2;
        if(key<arr[middle]){
            return recursionBinarySearch(arr,key,low,middle-1);
        }else if(key>arr[middle]){
            return recursionBinarySearch(arr,key,middle+1,high);
        }else{
            return middle;
        }
    }

    public static void main(String[] args) {
        int[] arr = {1,27,32,35,42,56,57,89};
        int middle=recursionBinarySearch(arr,42,0,7);
        System.out.println(middle);

    }
}

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