二分查找实现

public class Test {

    public static int binarySearch(Integer[] srcArray,int des) {
        //定义初始最小、最大索引
        int low = 0;
        int high = srcArray.length - 1;
        int max =0;int min=0;
        //确保不会出现重复查找，越界
        while (low <= high) {
            //计算出中间索引值
            int middle = (high + low)>>>1 ;//防止溢出
            if (des == srcArray[middle]) {
                return middle;
                //判断下限
            } else if (des < srcArray[middle]) {
                high = middle - 1;
                //判断上限
            } else {
                low = middle + 1;
            }
        }
        //若没有，则返回-1
        return -1;
    }

    public static void  main(String[] args){
        Integer[] a = {-8,-6,-5,-3,-2,-1,1};
        System.out.println(binarySearch(a,5));
        sort(a);
        sort2(a);
    }


    public static void sort(Integer[] srcArray){
        int max =0; int min = 0;
        int count =0;
        for(Integer i:srcArray){
            count++;
            if(max == 0){
                if(i<0){
                    max = i;
                }
            }else{
                if(i>max && i< 0 ){
                    max = i;
                }
            }
            if(min == 0){
                if(i>0){
                    min = i;
                }else {
                    if(i<min && i>0){
                        min = i;
                    }
                }
            }
        }
        System.out.println(max+" : "+min+" : "+ count);
    }

    public static void sort2(Integer[] srcArray){
        int max =0; int min = 0;
        int s1 = 0;
        int e2 = srcArray.length - 1;
        int mid = 0;
        int count =0;
        do{
            count++;
            mid = (s1+e2)>>>1;
            if(srcArray[mid]>0){
                e2 = mid;
            }else if(srcArray[mid] <0){
                s1=mid;
            }
        } while (srcArray[mid] !=0 && e2-s1>=2);
        if(srcArray[mid] ==0){
            for(int i = mid-1;i>=0;i--){
                count++;
                if(srcArray[i]<0){
                    max = srcArray[i];
                    break;
                }
            }
            for(int j = mid+1;j>=0&& j<e2;j++){
                count++;
                if(srcArray[j]>0){
                    min = srcArray[j];
                    break;
                }
            }
        }else{
            max = srcArray[s1];
            min = srcArray[e2];
        }
        System.out.println(max+" : "+min + " : "+ count);
    }
}