java 简单搜索算法

--无序查找
    public static int Search(int[] a,int key){
        for(int i=0;i<a.length;i++){
            if(key==a[i]){
                return i;
            }
        }
        return -1;
    }

--折半查找
    public static int BinarySearch(int[] a,int key){
        int min,max,mid;
        min=0;
        max=a.length-1;
        mid =(min+max)/2;
        while(key!=a[mid]){
            if(key>a[mid]){
                min=mid+1;
            }else{
                max=mid-1;
            }
            if(max<min)
                return -1;
            
            mid=(min+max)/2;
        }
        return mid;
    }

--折半查找优化
    public static int BinarySearch_2(int[] a,int key){
        int min,max,mid;
        min=0;
        max=a.length-1;    
        while(max>=min){
            mid =(min+max)>>1;
            if(key>a[mid]){
                min=mid+1;
            }else if(key<a[mid]){
                max=mid-1;
            }else{
                return mid;
            }
        }
        return -1;
    }