DFA for Strings not ending with “THE”
Problem – Accept Strings that not ending with substring “THE”. Check if a given string is ending with “the” or not. The different forms of “the” which are avoided in the end of the string are:
"THE", "ThE", "THe", "tHE", "thE", "The", "tHe" and "the"
All those strings that are ending with any of the above mentioned forms of “the” are not accepted.
Determinitis finite automata (DFA) of strings that not ending with “THE” –
The initial and starting state in this dfa is Qo
Approach used in the program –
In this program, consider the 4 states to be 0, 1, 2 and 3. Now let us take a variable named DFA which will be initially 0. Whenever any transition takes place, it will update the value of DFA with the number associated with new state.
Example : If a transition occurs from state 0 to state 1 then the value of DFA will be updated to 1. If a transition occurs from state 2 to state 3 then the value of dfa will be updated to 3. In this way, apply this algorithm on entire string and if in the end, then reach state 0, 1 or 2 then our string will be accepted otherwise not.
Input : XYzabCthe Output : NOT ACCEPTED Input : Themaliktth Output : ACCEPTED
C++
// CPP program to implement DFS that accepts // all string that do not end with "THE" #include <stdio.h> #include <string.h> // dfa tells the number associated // with the present state int dfa = 0; // This function is for // the starting state (zeroth) of DFA void start(char c) { // On receiving 'T' or 't' goto first state (1) if (c == 't' || c == 'T') dfa = 1; } // This function is for the first state of DFA void state1(char c) { // On receiving 'T' or 't' goto first state (1) if (c == 't' || c == 'T') dfa = 1; // On receiving 'H' or 'h' goto second state (2) else if (c == 'h' || c == 'H') dfa = 2; // else goto starting state (0) else dfa = 0; } // This function is for the second state of DFA void state2(char c) { // On receiving 'E' or 'e' goto third state (3) // else goto starting state (0) if (c == 'e' || c == 'E') dfa = 3; else dfa = 0; } // This function is for the third state of DFA void state3(char c) { // On receiving 'T' or 't' goto first state (1) // else goto starting state (0) if (c == 't' || c == 'T') dfa = 1; else dfa = 0; } bool isAccepted(char str[]) { // store length of string int len = strlen(str); for (int i=0; i < len; i++) { if (dfa == 0) start(str[i]); else if (dfa == 1) state1(str[i]); else if (dfa == 2) state2(str[i]); else state3(str[i]); } return (dfa != 3); } // driver code int main() { char str[] = "forTHEgeeks"; if (isAccepted(str) == true) printf("ACCEPTED\n"); else printf("NOT ACCEPTED\n"); return 0; } |
chevron_right
filter_none
Java
// Java program to implement DFS that accepts // all string that do not end with "THE" import java.util.*; class GFG { // dfa tells the number associated // with the present state static int dfa = 0; // This function is for // the starting state (zeroth) of DFA static void start(char c) { // On receiving 'T' or 't' goto first state (1) if (c == 't' || c == 'T') dfa = 1; } // This function is for the first state of DFA static void state1(char c) { // On receiving 'T' or 't' goto first state (1) if (c == 't' || c == 'T') dfa = 1; // On receiving 'H' or 'h' goto second state (2) else if (c == 'h' || c == 'H') dfa = 2; // else goto starting state (0) else dfa = 0; } // This function is for the second state of DFA static void state2(char c) { // On receiving 'E' or 'e' goto third state (3) // else goto starting state (0) if (c == 'e' || c == 'E') dfa = 3; else dfa = 0; } // This function is for the third state of DFA static void state3(char c) { // On receiving 'T' or 't' goto first state (1) // else goto starting state (0) if (c == 't' || c == 'T') dfa = 1; else dfa = 0; } static boolean isAccepted(char str[]) { // store length of string int len = str.length; for (int i=0; i < len; i++) { if (dfa == 0) start(str[i]); else if (dfa == 1) state1(str[i]); else if (dfa == 2) state2(str[i]); else state3(str[i]); } return (dfa != 3); } // Driver code public static void main(String[] args) { char str[] = "forTHEgeeks".toCharArray(); if (isAccepted(str) == true) System.out.println("ACCEPTED\n"); else System.out.println("NOT ACCEPTED\n"); } } /* This code is contributed by PrinciRaj1992 */ |
chevron_right
filter_none
Python3
# Python3 program to implement DFS that accepts # all stringing that do not end with "THE" # This function is for the starting # state (zeroth) of DFA def start(c): # On receiving 'T' or 't' goto # first state (1) if (c == 't' or c == 'T'): dfa=1 # This function is for the first state of DFA def state1(c): # On receiving 'T' or 't' goto first state (1) if (c == 't' or c == 'T'): dfa = 1 # On receiving 'H' or 'h' goto second state (2) elif (c == 'h' or c == 'H'): dfa = 2 # else goto starting state (0) else: dfa = 0 # This function is for the second state of DFA def state2(c): # On receiving 'E' or 'e' goto third # state (3) else goto starting state (0) if (c == 'e' or c == 'E'): dfa = 3 else: dfa = 0 # This function is for the third state of DFA def state3(c): # On receiving 'T' or 't' goto first # state (1) else goto starting state (0) if (c == 't' or c == 'T'): dfa = 1 else: dfa = 0 def isAccepted(string): # store length of stringing length = len(string) for i in range(length): if (dfa == 0): start(string[i]) elif (dfa == 1): state1(string[i]) elif (dfa == 2): state2(string[i]) else: state3(string[i]) return (dfa != 3) # Driver Code if __name__ == "__main__" : string="forTHEgeeks" # dfa tells the number associated # with the present state dfa = 0 if isAccepted(string): print("ACCEPTED") else: print("NOT ACCEPTED") # This code is contributed by SHUBHAMSINGH10 |
chevron_right
filter_none
C#
// C# program to implement DFS that accepts // all string that do not end with "THE" using System; class GFG { // dfa tells the number associated // with the present state static int dfa = 0; // This function is for // the starting state (zeroth) of DFA static void start(char c) { // On receiving 'T' or 't' goto first state (1) if (c == 't' || c == 'T') dfa = 1; } // This function is for the first state of DFA static void state1(char c) { // On receiving 'T' or 't' goto first state (1) if (c == 't' || c == 'T') dfa = 1; // On receiving 'H' or 'h' goto second state (2) else if (c == 'h' || c == 'H') dfa = 2; // else goto starting state (0) else dfa = 0; } // This function is for the second state of DFA static void state2(char c) { // On receiving 'E' or 'e' goto third state (3) // else goto starting state (0) if (c == 'e' || c == 'E') dfa = 3; else dfa = 0; } // This function is for the third state of DFA static void state3(char c) { // On receiving 'T' or 't' goto first state (1) // else goto starting state (0) if (c == 't' || c == 'T') dfa = 1; else dfa = 0; } static bool isAccepted(char []str) { // store length of string int len = str.Length; for (int i=0; i < len; i++) { if (dfa == 0) start(str[i]); else if (dfa == 1) state1(str[i]); else if (dfa == 2) state2(str[i]); else state3(str[i]); } return (dfa != 3); } // Driver code static public void Main () { char []str = "forTHEgeeks".ToCharArray(); if (isAccepted(str) == true) Console.WriteLine("ACCEPTED\n"); else Console.WriteLine("NOT ACCEPTED\n"); } } /* This code is contributed by ajit. */ |
chevron_right
filter_none
PHP
<?php // PHP program to implement DFS // that accepts all string that // do not end with "THE" // dfa tells the number associated // with the present state $dfa = 0; // This function is for the // starting state (zeroth) of DFA function start($c) { global $dfa; // On receiving 'T' or 't' // goto first state (1) if ($c == 't' || $c == 'T') $dfa = 1; } // This function is for // the first state of DFA function state1($c) { global $dfa; // On receiving 'T' or 't' // goto first state (1) if ($c == 't' || $c == 'T') $dfa = 1; // On receiving 'H' or 'h' // goto second state (2) else if ($c == 'h' || $c == 'H') $dfa = 2; // else goto starting state (0) else $dfa = 0; } // This function is for // the second state of DFA function state2($c) { global $dfa; // On receiving 'E' or 'e' // goto third state (3) else // goto starting state (0) if ($c == 'e' || $c == 'E') $dfa = 3; else $dfa = 0; } // This function is for // the third state of DFA function state3($c) { global $dfa; // On receiving 'T' or 't' // goto first state (1) else // goto starting state (0) if ($c == 't' || $c == 'T') $dfa = 1; else $dfa = 0; } function isAccepted($str) { global $dfa; // store length of string $len = strlen($str); for ($i=0; $i < $len; $i++) { if ($dfa == 0) start($str[$i]); else if ($dfa == 1) state1($str[$i]); else if ($dfa == 2) state2($str[$i]); else state3($str[$i]); } return ($dfa != 3); } // Driver Code $str = "forTHEgeeks"; if (isAccepted($str) == true) echo "ACCEPTED\n"; else echo "NOT ACCEPTED\n"; // This code is contributed by m_kit ?> |
chevron_right
filter_none
Output :
ACCEPTED
The time complexity of this program is O(n)
Don’t stop now and take your learning to the next level. Learn all the important concepts of Data Structures and Algorithms with the help of the most trusted course: DSA Self Paced. Become industry ready at a student-friendly price.
Recommended Posts:
- Program to build a DFA that accepts strings starting and ending with different character
- Check if strings are rotations of each other or not | Set 2
- Count strings that end with the given pattern
- Find strings that end with a given suffix
- Count of all sub-strings with sum of weights at most K
- DFA for strings not containing consecutive two a's and starting with 'a'
- Check whether two strings contain same characters in same order
- String matching with * (that matches with any) in any of the two strings
- Count of sub-strings with equal consecutive 0's and 1's
- Count all sub-strings with weight of characters atmost K
- Build a DFA to accept Binary strings that starts or ends with "01"
- Program to build a DFA to accept strings that start and end with same character
- NFA to accept strings that has atleast one character occurring in a multiple of 3
- Python program to find uncommon words from two Strings
- Sort the strings based on the numbers of matchsticks required to represent them
- For each lowercase English alphabet find the count of strings having these alphabets
- Total length of string from given Array of strings composed using given characters
- Sort an array of strings based on the frequency of good words in them
- NFA machines accepting all strings that ends or not ends with substring 'ab'
- Strings formed from given characters without any consecutive repeating characters
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
- Smallest number greater than n that can be represented as a sum of distinct power of k
- Build a DFA to accept Binary strings that starts or ends with "01"
- How to validate MAC address using Regular Expression
- Count the number of clumps in the given Array
- Count of distinct pair sum between two 1 to N value Arrays