java做题记录

package ch2;
import java.util.Scanner;
public class CG0311_2 {
    public static void main(String [] args) {
        Scanner sc = new Scanner(System.in); 
        long  res=0 ,base = 1;
        String str;
        str = sc.next();
        int len = str.length();
        for(int i = len-1;i>=0;i--) {
            if( str.charAt(i)==‘1‘ ) {
                res += base;
            }
            base*=2;
        } 
        System.out.println(res);
        sc.close();
    }
}

package ch2;
import java.util.Scanner;
public class CG031101 {
    public static void main( String [] args ) { 
        Scanner in = new Scanner(System.in);
        long a,b;
        a = in.nextInt();
        b = in.nextInt(); 
        System.out.printf("128-bit hexadecimal number:\n%016x%016x\n",a,b);
        a = a<<1;
        if( b<=-1 )    a=a+1; 
        b=b<<1;
        System.out.printf("After doubling:\n%016x%016x\n",a,b);
    }
}