2.DESIGN AND IMPLEMENTATION OF TABLES USED IN A TRANSLATOR

#include <stdio.h>
#include <string.h>

int isValidString(char *str) {
    int count_a = 0, count_b = 0;
    int state = 0; // q0

    printf("\nTransition Table\n");
    printf("Current State | Input | Next State\n");
    printf("-------------------------------\n");

    for (int i = 0; str[i] != '\0'; i++) {
        char ch = str[i];

        printf("q%d            |  %c    | ", state, ch);

        if (state == 0) {
            if (ch == 'a') {
                count_a++;
                printf("q0\n");
            } else if (ch == 'b') {
                state = 1;
                count_b++;
                printf("q1\n");
            } else {
                printf("Reject (Invalid character)\n");
                return 0;
            }
        } else if (state == 1) {
            if (ch == 'b') {
                count_b++;
                printf("q1\n");
            } else if (ch == 'a') {
                printf("Reject (a after b)\n");
                return 0;
            } else {
                printf("Reject (Invalid character)\n");
                return 0;
            }
        }
    }

    // Final validation
    if (state == 1 && count_a == count_b && count_a > 0) {
        printf("\nThe string is valid (a^n b^n)\n");
        return 1;
    } else {
        printf("\nThe string is invalid (a^n b^n)\n");
        return 0;
    }
}

int main() {
    char input[100];
    printf("Enter the string: ");
    scanf("%99s", input); // Prevent buffer overflow
    isValidString(input);
    return 0;
}