黑马程序员-折半查找及进制的转换

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折半查找
class Demo
{
public static void main(String[] args)
{
int[] arr ={1,3,5,7,9,11};
int index = halfSearch(arr,9);
System.out.println("index="+index);

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

进制的转换
class Demo2
{
public static void main(String[] args)
{
toBinary(60);
System.out.println();
toOctal(60);
System.out.println();
toHex(60);
}
public static void toBinary(int num)
{
trans(num,1,1);
}
public static void toOctal(int num)
{
trans(num,7,3);
}
public static void toHex(int num)
{
trans(num,15,4);
}
public static void trans(int num, int base, int offset)
{
char[] ch={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
char[] arr= new char[32];
int pos = arr.length;
while(num!=0)
{
int temp = num & base;
arr[--pos] = ch[temp];
num=num>>>offset;
}
for(int x=pos; x<arr.length; x++)
{
System.out.print(arr[x]);
}
}
}

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