折半算法JAVA实现

折半算法实现方法一：循环实现

public static int biSearch(int[] arr,int num) {
        int low = 0;
        int high = arr.length-1;
        int middle;

        while(low<=high){
            middle = (low+high)/2;
            if(num<arr[middle]) {
                high = middle-1;
            } else if(num>arr[middle]) {
                low = middle+1;
            } else {
                return middle+1;
            }
        }
        return -1;
    }

折半算法实现方法二：递归实现

public static int biSearch(int[] arr,int num,int low,int high) {
        int middle;
        middle = (low+high)/2;

        if(num<arr[middle]) {
            return biSearch(arr,num,low,middle-1);
        } else if(num>arr[middle]) {
            return biSearch(arr,num,middle+1,high);
        } else {
            return middle+1;
        }
    }