Question

5 Given the state table of a Moore machine and then input string, produce the output string generated by the machine.

6 Give in the state table of Mealy machine and an input string, produce the output using string generated by the machine.

I need an Algorithm/Code that can perform the actions above. In python.

Answer 1

# Python3 Program for Bad Character Heuristic
# of Boyer Moore String Matching Algorithm

NO_OF_CHARS = 256

def badCharHeuristic(string, size):
   '''
   The preprocessing function for
   Boyer Moore's bad character heuristic
   '''

   # Initialize all occurence as -1
   badChar = [-1]*NO_OF_CHARS

   # Fill the actual value of last occurence
   for i in range(size):
       badChar[ord(string[i])] = i;

   # retun initialized list
   return badChar

def search(txt, pat):
   '''
   A pattern searching function that uses Bad Character
   Heuristic of Boyer Moore Algorithm
   '''
   m = len(pat)
   n = len(txt)

   # create the bad character list by calling
   # the preprocessing function badCharHeuristic()
   # for given pattern
   badChar = badCharHeuristic(pat, m)

   # s is shift of the pattern with respect to text
   s = 0
   while(s <= n-m):
       j = m-1

       # Keep reducing index j of pattern while
       # characters of pattern and text are matching
       # at this shift s
       while j>=0 and pat[j] == txt[s+j]:
           j -= 1

       # If the pattern is present at current shift,
       # then index j will become -1 after the above loop
       if j<0:
           print("Pattern occur at shift = {}".format(s))

           '''     
               Shift the pattern so that the next character in text
                   aligns with the last occurrence of it in pattern.
               The condition s+m < n is necessary for the case when
               pattern occurs at the end of text
           '''
           s += (m-badChar[ord(txt[s+m])] if s+m<n else 1)
       else:
           '''
           Shift the pattern so that the bad character in text
           aligns with the last occurrence of it in pattern. The
           max function is used to make sure that we get a positive
           shift. We may get a negative shift if the last occurrence
           of bad character in pattern is on the right side of the
           current character.
           '''
           s += max(1, j-badChar[ord(txt[s+j])])

# Driver program to test above funtion
def main():
   txt = "ABAAABCD"
   pat = "ABC"
   search(txt, pat)

if __name__ == '__main__':
   main()