二分查找Java實現

public class BinSearch {

    //遞歸實現
    public static int binSearch(int[]arr,int low,int high,int key){
        if(low>high||key<arr[low]||key>arr[high]){
            return -1 ;
        }
        int mid = low+(high-low) / 2;
        if (arr[mid] < key) {
            return binSearch(arr, mid + 1, high, key);
        } else if (arr[mid] > key) {
            return binSearch(arr, low, mid - 1, key);
        } else {
            return mid;
        }
    }

    //非遞歸循環實現
    public static int binSearch1(int[]arr,int key){
        int low=0;
        int high=arr.length-1;
        
        while(low<=high){
            int mid=low+(high-low)/2;
            if(arr[mid]>key){
                low=mid+1;
            }else if(arr[mid]<key){
                high=mid-1;
            }else{
                return mid;
            }
        }
        return -1;
    }

    public static void main(String[] args) {
        int[] arr=new int[]{3,4,5,6,7,8};
        System.out.println(binSearch(arr,0,arr.length-1,5));
        System.out.println(binSearch1(arr,5));
    }
}