CODEWITHSUNDEEP
pythonarrays
shubhamj
shubhamj

Reputation: 938

2d Array Python :list index out of range

I am new to Python programming and I am trying to write code to check if a DFA( Deterministic Finite Automata) has empty language or not.

I am using 2-d array to store state of the DFA. On executing the code I keep getting list index out of range. How can I fix this?

Below is the code 

top=-1
count=0
n=int(input("\nEnter the no of states"))
mat=[[]]
b=[]
print("\nEnter the transition table")
for i in range(0,n):
   for j in range(0,n):
    mat.append(input())
finalState=input("\nEnter the final state:")
startState=input("\nEnter the start state:")      

for i in range(0,n):
   for j in range(0,n):
      if mat[i][j]:
        b[++top]=j
for k in range(top):
      if b[k]==finalState:
      count+=1
if count>0:
print("\nLanguage is  not empty")
else:
print("\nLanguage is empty")

Upvotes: 0

Views: 6815

Answers (1)

Kevin
Kevin

Reputation: 76254

when you make a 2x2 table, you want mat to be [[1,2],[3,4]], but you're getting [[],1,2,3,4] right now.

Instead, try:

mat = []
for i in range(n):
    row = []
    for j in range(n):
        row.append(input())
    mat.append(row)

Also, Python does not have a "++" operator, so b[++top]=j is the same as b[top] = j. If you want to increment top, you have to do that on its own line before you use it to index the list.

On top of that, b has zero elements, so indexing it in any way will cause a crash. If you're trying to increase the size of b by adding new items to it, use append. Then you don't need a top variable at all.

b.append(j)

Upvotes: 6

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