进制转化

//除留取余法
    public String solve (int M, int N) {
        int flag = 0;
        //考虑M为负数的情况
        if(M<0) {
            M = -M;
            flag = 1;
        }
        // write code here
       StringBuilder sb = new StringBuilder();
       while(M!=0){
           int ys = M%N;
           M = M/N;
           char t = '0';
           if(ys<10) t = (char)(t+(ys-0));
           else t = (char)('A'+(ys-10));
           sb.append(t);
       }
        String ress = sb.reverse().toString();
        return flag==1?"-"+ress:ress;
    }