[Python][CheckiO] Solve Disposable teleports

Firstly I thought it was the Eular Circuit problem, so it took me couples of days to review the Eular Path and the Eular Circuit. During the implementation, I found it was not that hard and could be solved applying DFS algorithm.


Here's the source code

 def list_sub(l_a, l_b):  
   return [i for i in l_a if not i in l_b or l_b.remove(i)] 

 
 def bi_direction_list_sub(l_a, l_b):  
   l_valid_path = [ ]  
   for i in l_a:  
     rev_i = (i % 10) * 10 + (i // 10)  
     if not i in l_b:  
       if not rev_i in l_b:  
         l_valid_path.append(i)  
   return l_valid_path 

 
 def get_map_list(teleports_string):  
   l_map = [ int(i) for i in teleports_string.split(',')]  
   l_map_bi_direction = [i for i in l_map]  
   for p in l_map:  
     p_rev = (p % 10) * 10 + (p // 10)  
     l_map_bi_direction.append(p_rev)  
   sorted(l_map_bi_direction)  
   return l_map_bi_direction 

 
 def get_path(l_tel, l_ret, last_path, last_pop):  
   l_working_path = bi_direction_list_sub(l_tel, l_ret)  
   sorted(l_working_path)  
   for p in l_working_path:  
     if str(p)[0] == str(last_path)[ len(str(last_path)) - 1 ]:  
       if every_node_be_traversed(l_ret) == False:  
         if p > last_pop:  
           return p  
   return 'dead'  

 def every_node_be_traversed(l_ret):  
   l_traversed_node = [str(path)[0] for path in l_ret]  
   for i in range(1, 9):  
     if not str(i) in l_traversed_node:  
       return False  
   if str(l_ret[len(l_ret) - 1])[1] != '1':  
     return False  
   return True  

 def remove_path_from_candidate(l_tmp_tel, path):  
   rev_path = (path % 10) * 10 + (path // 10 )  
   if path in l_tmp_tel:  
     l_tmp_tel.remove(path)  
   if rev_path in l_tmp_tel:  
     l_tmp_tel.remove(rev_path) 

 
 def add_candidate(l_tmp_tel, path):  
   rev_path = (path % 10) * 10 + (path // 10 )  
   if not path in l_tmp_tel:  
     l_tmp_tel.append(path)  
   if not rev_path in l_tmp_tel:  
     l_tmp_tel.append(rev_path)

  
 def checkio(teleports_string):  
   l_ret = [ ]  
   l_tel = get_map_list(teleports_string)  
   l_tmp_tel = [i for i in l_tel]  
   last_path = 1  
   last_pop = 1  
   while every_node_be_traversed(l_ret) == False:  
     path = get_path(l_tmp_tel, l_ret, last_path, last_pop)  
     if path == 'dead': #dead end  
       if len(l_ret) == 0:  
         last_path = 1  
         last_pop = 1  
       else:  
         last_pop = l_ret.pop()  
         add_candidate(l_tmp_tel, last_pop)  
         if str(last_pop)[0] == '1':  
           last_path = 1  
           last = 1  
           continue  
         else:  
           last_path = l_ret[ len(l_ret) - 1]  
       continue  
     last_pop = 1  
     last_path = path  
     l_ret.append(path)  
     remove_path_from_candidate(l_tmp_tel, path)  
     l_tmp_tel = sorted(l_tmp_tel)  
     l_str_ret = [str(i)[0] for i in l_ret]  
   ret = ''.join(l_str_ret)+'1'  
   return ret