折半查找
class arr{
public static void main(String[] args)
{
System.out.println("hello world");
}
}
class arr{
public static void main(String[] args)
{
int[] arr={3,1,5,4,2,9};
int index=getindex(arr,2);
System.out.println(index);
}
public static int getindex(int[] arr,int key)
{
for(int x=0;x<arr.length;x++)
{
if(arr[x]==key)
return x;
}
return -1;
}
public static int getindex2(int[] arr,int key)
{
int min,max,mid;
mid=(arr.length-1)/2;
min=0;
max=arr.length-1;
while(arr[mid]!=key)
{
if(arr[mid]>key)
min=mid+1;
else if(key>arr[mid])
max=mid-1;
if(min>max) return -1;
mid=(max+mid)/2;
}
}
}
折半的第二种方式
进制转换
class arr{
public static void tobin(int num)
{
StringBuffer sb=new StringBuffer();
while(num>0)
{
System.out.println(num%2);
num=num/2;
}
System.out.println(sb.reverse());
}
public static void tohex(int num)
{
int n1=num & 15;
if(n1-10+'a'>9)
{
}
}
public static void main(String[] args)
{
int num=10;
tobin(num);
}