Python : The merge of two lists and maintain the order

Question

I want to merge 2 lists in one list, and in this one list I can find the elements of the two lists at the same order for example: input:

['10','22','3','4','5']
['22','3','5']

the output should be:

['10','22','3','4','5']

The goal is to combine multiple sequences of tasks to do in one sequence in which we can pass all the tasks. I used the code below but it repeats many tasks that we can eliminate logically, I want to optimize it more.

 def merge(L,R):
    S=[]
    n=min(len(L),len(R))
    for i in range(n):
        if L[i]==R[i]:
            S.append(L[i])
        else: 
            S.append(L[i])
            S.append(R[i])
    if len(L)>len(R):
        return(S+list(k for k in L[n:]))
    if len(R)>len(L):
        return(S+list(k for k in R[n:]))
    if len(L)==len(R):
        return(S)

# n is the number of tasks written in a text file before tasks and each task is written on a line

n=int(input())
resultat=[]
for i in range(n):
    line=input().split()
    resultat=merge(resultat,line)
print(resultat)

Answer 1

Your question is unclear.

In case you want to merge the lists of tasks and execute each task once only, we can use sets:

l1=['A' ,'B' ,'C' ,'D' ,'F']
l2=['C', 'D', 'E', 'F']
l3=['A', 'B', 'C', 'F']
l4=['A', 'C', 'B', 'F']
l5=['A','C' ,'D' ,'E' ,'F'] 
l6=['B', 'C', 'D', 'E', 'F']

import itertools as it
s = set(it.chain(l1, l1, l3, l4, l5, l6)))
print(list(s))

produces

['A', 'B', 'F', 'E', 'D', 'C']

Else, if you want a unique set of tasks at each step of every list in parallel

lo = [e for t in it.zip_longest(l1, l2, l3, l4, l5, l6) for e in set(t) if e is not None]
print(lo)

produces

['B', 'A', 'C', 'B', 'D', 'C', 'B', 'E', 'D', 'C', 'F', 'E', 'D', 'F']

In case the input lists vary in number, create a list of lists and check out itertools.chain.from_iterable