Compiler_Designing_Concepts/Recdes2.java at master · mohith10/Compiler_Designing_Concepts · GitHub

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//S->bAc
//A->re|r

import java.util.*;
import java.io.*;

class Recdes2
{
	static int ptr;
	static char[] input;
	public static void main(String args[])
	{
		System.out.println("Input the string to be checked :");
		String s=new Scanner(System.in).nextLine();
		input=s.toCharArray();
		ptr=0;
		boolean result=S();
		if(result && ptr==input.length)
			System.out.println("ACCEPTED :)");
		else System.out.println("REJECTED :(");
	}

	static boolean S()
	{
		int fallback=ptr;
		if(input[ptr++]!='b')
		{
			ptr=fallback;
			return false;
		}
		if(A()==false)
		{
				ptr=fallback;
				return false;
		}
		if(input[ptr++]!='c')
		{
				ptr=fallback;
				return false;
		}
		return true;

	}

	static boolean A()
	{
		int fallback=ptr;
		if(input[ptr]=='r'&& input[ptr+1]!='e')
			{
				ptr++;
				return true;
			}
		else
		{
			if(input[ptr++]!='r')
				{
					ptr=fallback;
					return false;
				}
			if(input[ptr++]!='e')
				{
					ptr=fallback;
					return false;
				}
				return true;
		}
	}
}