Interview programming questions TEG

There are two text files a.txt, b.txt, the format is as follows:
a.txt:
1 abc
2 cde
3 bf5
5 dnf b.txt
:
5 dnf
1 poi
2 teg
4 afp The
above two file separators are tab, Please write a script in python to write the difference of the contents of the above two files into a file and sort them in ascending order according to the numbers in the first column.

# coding:utf-8
# @Time    : 2018/5/4 14:43
# @Author  : vglede
# @File    : compare_file.py
# @Software: PyCharm Community Edition

import os
import sys


BASE_DIR=os.path.abspath('.')

sys.path.append(os.path.join(BASE_DIR,"conf"))
sys.path.append("F:\\pyscript\\py2\\conf\\")
#print  sys.argv
a_file_path="F:\\pyscript\\py2\\conf\\a.txt"
b_file_path="F:\\pyscript\\py2\\conf\\b.txt"
c_file_path="F:\\pyscript\\py2\\conf\\c.txt"

class Operator_File:
    def read_file(self,Filename):
        self.file = Filename
        with open(self.file, ' r ' ) as f:
             #Remove the \n of the read file 
            return   '' .join(f.readlines()).strip( ' \n ' ).split( ' \n ' )

    def write_file(self,Filename,contents,type_flag):
        self.file = Filename
        with open(self.file,type_flag) as f:
            if isinstance(contents,list) or  isinstance(contents,tuple):for f_lines in contents:
                    f.write('%s\n'%f_lines)
            elif isinstance(contents,str):
                f.write(contents)
            elif isinstance(contents,dict):
                for item in contents.items():
                    f.write(item)

class FileCompare:
    def compare_file_diff(self,src_list1,src_list2):
        dest_list=[]
        for line in src_list1:
            if line not in src_list2:
                dest_list.append(line)
        return dest_list

#get the object of the class
of=Operator_File()
a_list=of.read_file(a_file_path)
b_list=of.read_file(b_file_path)
#print a_list
#print b_list

cmf=FileCompare()
dest_list =cmf.compare_file_diff(a_list,b_list)+ cmf.compare_file_diff(b_list,a_list)
 # print dest_list 
# print type(dest_list) 
# sort is not written by default (reverse=False) in ascending order 
# , if you need to sort in descending order reverse=True Just dest_list.sort 
(reverse= False)
 # print dest_list 

of.write_file(c_file_path,dest_list, ' w+ ' )