*/ This program calculates the value of Ackerman function A(x,y)
   n0n-recursively; written in "C" by Anilkumar C.D. on 8th Aug 2008
   It uses 2 functions ack_11 and ack_12.

   Increase the capacity of the array X1[n] for higher values of x and y,
   and here the array size is  "100", as it's a safe value for the computer/*
   
   

#include<stdio.h>

void main()

{
	int x,y,p,q;
	int ack_11(int x, int y);
	int ack_12(int x, int y);

	int total = 0;
	
	printf("Enter va;ues of x and y : ");
	scanf("%d %d",&x,&y);
	p=x;;
	q=y;
	if (x>=1 && y>=1)
		total=ack_11(x,y);
	else if(x>0 && y==0)
		total=ack_12(x,y);
	else
		total=y+1;
	printf(" \n A( %d, %d )= %d ",p,q,total);
	
 }
	

 int ack_11(int x, int y)
 {
	 int n, x1[100];// array x1[n] initialized for 100 values(increase it if result is wrong)
	 int total;
	 
	 n=1;
	 for (;x;)
	 {
		 x1[n]=x-1;
		 y--;
		 n++;
		 if (y==0)
		 {
			 x--;
			 y++;
			 if(x==1)
			 {
				 y=y+2;
				 n--;
				  
			 }
			 else if(x==0)
			 {
				 n--;
				 y++;
				 while(x1[n]==0 && n>1)
				 {
					 	 y++;
						 n--;
						 x=x1[n];
						 					
				 }
				 
			 }
		 }
	 
	 }
	 total=y+1;
	 return(total);
 }

				 
 int ack_12(int x, int y)
 {
	int n, x1[100];
	int total;
	 
	n=1;
	y++;
	for (;x;)
	{
		if (x==1)
		{
			total=y+1;
			x--;
		}
		else
		{
			x--;
			for (;x;)
			{
				x1[n]=x-1;
				n++;
				y--;
				if (y==0)
				{
					x--;
					y++;
					if(x==1)
					{
						y=y+2;
						n--;
					}
					else if(x==0)
					{
						n--;
						y++;
						while(x1[n]==0 && n>1)
						{
							y++;
							n--;
							x=x1[n];
							
						}
					}
				}
			}
		}
	}
	total=y+1;
	return(total);	
}