CODEWITHSUNDEEP
pythonfinite-automatanfa
user3655617
user3655617

Reputation: 41

Implementing an NFA in Python

I am trying to implement an NFA in python and I have made some progress however I am stuck because I need to use a 3d array and the indices of the array need to correspond to the current state and the current character to be processed. I have to to use integers as indices of the array and I am trying to convert from string data type to int for this. However, I am getting the error: "list indices must be integers, not str" , any help will be much appreciated. Here is the code I've written so far:

"""Initialize States"""
q0=0
q1=1
q2=2

i=0

finstate=q2  #final state is q2

array=[[[0],[0,1]],[[2],[2]],[[],[]]]  #3d array for state transitions

def accepts(state, word):
    global i
    if i==len(word):
        return state==finstate  #if last state is final state accept

    char=word[i]
    i+=1
    int(char) #covert char to int

    nextstates=array[state][char]

    for i in range(len(word)):
        if accepts(nextstates, word):  #recursion
            return True
    return False

def main():
    string= "01" #sample input 
    if accepts(q0, string):
        print("accepts")
    else:
        print("rejects")

main()

Upvotes: 2

Views: 6004

Answers (1)

Subhasis Das
Subhasis Das

Reputation: 1677

Well assuming the remaining of your code is correct, you should have something like

char = word[i]
i += 1
intval = int(char)
nextstates=array[state][intval]

Upvotes: 1

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