cd4 left recursion

//S->aS|b no left recursion
//A->Aa|Ab|c
//A->cA'
//A'->a|bA'|e

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

#define MAX 100

void checkLeftRecursion(char nonTerminal, char *productions) {
    char alpha[MAX] = "", beta[MAX] = "";
    int isLeftRecursive = 0;

    for (char *token = strtok(productions, "|"); token; token = strtok(NULL, "|")) {
        if (token[0] == nonTerminal) {
            isLeftRecursive = 1;
            strcat(alpha, token + 1);
            strcat(alpha, "|");
        } else {
            strcat(beta, token);
            strcat(beta, "|");
        }
    }

    if (isLeftRecursive) {
        alpha[strlen(alpha) - 1] = '\0';
        beta[strlen(beta) - 1] = '\0';
        printf("Left Recursive Grammar Detected.\n");
        printf("%c -> %s%c'\n", nonTerminal, beta, nonTerminal);
        printf("%c' -> %s%c'|e\n", nonTerminal, alpha, nonTerminal);
    } else {
        printf("No Left Recursion detected.\n");
    }
}

int main() {
    char input[MAX], nonTerminal, productions[MAX];

    printf("Enter the production rule (e.g., A->Aa|b): ");
    fgets(input, MAX, stdin);
    input[strcspn(input, "\n")] = '\0';

    if (!isupper(input[0]) || strncmp(input + 1, "->", 2) != 0) {
        printf("Error: Invalid production rule format.\n");
        return 0;
    }

    nonTerminal = input[0];
    strcpy(productions, input + 3);

    checkLeftRecursion(nonTerminal, productions);
    return 0;
}