toc/DFA2.cpp at master · bikalpasharma/toc · GitHub

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// C program to implement DFS that accepts L = { a^n b^m ; (n)mod 2=0, m>=1 }
#include <stdio.h>
#include <string.h>

int dfa = 0;

// This function is for the first state (Q0) of DFA

void start(char c)
{
	if (c == 'a') {
		dfa = 1;
	}
	else if (c == 'b') {
		dfa = 3;
	}

	else {
		dfa = -1;
	}
}

// This function is for the first state (Q1) of DFA
void state1(char c)
{
	if (c == 'a') {
		dfa = 2;
	}
	else if (c == 'b') {
		dfa = 4;
	}
	else {
		dfa = -1;
	}
}

// This function is for the second state (Q2) of DFA
void state2(char c)
{
	if (c == 'b') {
		dfa = 3;
	}
	else if (c == 'a') {
		dfa = 1;
	}
	else {
		dfa = -1;
	}
}

// This function is for the third state (Q3)of DFA
void state3(char c)
{
	if (c == 'b') {
		dfa = 3;
	}
	else if (c == 'a') {
		dfa = 4;
	}
	else {
		dfa = -1;
	}
}

// This function is for the fourth state (Q4) of DFA
void state4(char c)
{
	dfa = -1;
}

int isAccepted(char str[])
{
	int i, 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 if (dfa == 3)
			state3(str[i]);

		else if (dfa == 4)
			state4(str[i]);
		else
			return 0;
	}
	if (dfa == 3)
		return 1;
	else
		return 0;
}

int main()
{
	char str[] = "aaaaaabbbb";

	if (isAccepted(str))
		printf("ACCEPTED\n");
	else
		printf("NOT ACCEPTED\n");
	return 0;
}