题意不用再解释做法是求两个二进制数的最大公约数字然后以二进制输出

import java.io.*;import java.math.BigInteger;import java.util.*;public class Main {    static PrintWriter out = new PrintWriter(new BufferedWriter(            new OutputStreamWriter(System.out)));    public static void main(String[] args) throws IOException {        Scan scan = new Scan();        int t = scan.nextInt();        for (int c = 1; c <= t; c++) {            String s = scan.next();            BigInteger a = new BigInteger(s,2);            s = scan.next();            BigInteger b = new BigInteger(s,2);            out.println("Case #" + c + ": " + a.gcd(b).toString(2));        }        out.flush();    }    private static double max(double d, double e) {        if (d - e > 0)            return d;        return e;    }}class Scan {    BufferedReader buffer;    StringTokenizer tok;    Scan() {        buffer = new BufferedReader(new InputStreamReader(System.in));    }    boolean hasNext() {        while (tok == null || !tok.hasMoreElements()) {            try {                tok = new StringTokenizer(buffer.readLine());            } catch (Exception e) {                return false;            }        }        return true;    }    String next() {        if (hasNext())            return tok.nextToken();        return null;    }    String nextLine() {        String s = null;        try {            s = buffer.readLine();        } catch (Exception e) {            return null;        }        return s;    }    char nextChar() {        try {            return ((char) buffer.read());        } catch (Exception e) {        }        return ‘\0‘;    }    int nextInt() {        return Integer.parseInt(next());    }    long nextLong() {        return Long.parseLong(next());    }    double nextDouble() {        return Double.parseDouble(next());    }}