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;
     }