[SOLVED] this code segment sticks in a loop when it enters the push() function....

mscoder · 08-06-2011, 05:51 AM

int stack[100] and int top=-1 have been defined globally...thanks in advance for your help...

Code:

#include<stdio.h>



int pop();
void push(int);
void function(int,int *);
int stack[1000];
int top=-1;
int count=0;


int main()
{
        int t;

        int pile_count[100];
        int stone_count[100];
        printf("\nEnter the number of test cases");
        scanf("%d",&t);
        int i,j;
        for (i=0;i<t;i++)
        {
                count=0;


                scanf("\n%d",&pile_count[i]);


                for(j=0;j<pile_count[i];j++)
                {

                        scanf(" %d",&stone_count[j]);

                }

        function(pile_count[i],stone_count);
        }

     
        return(0);
}

void function(int count1,int *array_stncnt)
{ 
        int i,n,index;
        int *p=array_stncnt;
        for(i=0;i<count1;i++)
        {
                if(p[i]>=i)
                {
                        push(i);  /*Push called*/
                        push(p[i]);
                }
                else{}

        }

        while(top!=-1)
        {
                n=pop();
                index=pop();
                n=n-index;
                if(n>=index)
                {
                        push(index);
                        push(n);
                }
                else{}
                count++;
        }
        if(count%2==0)
        {
                printf("\nBOB WINS");
        }
        else
        {
                printf("\nALICE WINS");
        }

}



void push(int data)
{

                printf("\Push fn called\n");
                top++;
                stack[top]=data;
                printf("\nTHe data aded to stack is %d",stack[top]);
}

int pop()
{
                int data;
                data=stack[top];
                top--;
                return(data);
}

johnsfine · 08-06-2011, 06:20 AM

You haven't provided enough info to diagnose the problem.

The code you posted looks OK, so I think the bug is in some of the code you didn't post.

How big is the count input to function()? If it is more than 50, then you might be exceeding the end of the stack array.

Whatever is going wrong, "sticks in a loop when it enters the push() function" is a very unlikely result. What makes you think that is happening?

mscoder · 08-06-2011, 06:53 AM

@jonsfine....i posted the entire code..the count input i was giving for testing was 3...i cant find any reason for the prblm..

johnsfine · 08-06-2011, 07:18 AM

Quote:

Originally Posted by mscoder

Code:

                printf("\Push fn called\n");

I didn't notice that typo until I tried to compile the code.

What is the \P doing?

But once I ran the program I understood the bug. In fact you had posted enough the first time and I just didn't notice the right detail before running the program:

Quote:

for(i=0;i<count1;i++)
...
push(i); /*Push called*/

Note your first index is 0.

Quote:

n=pop();
index=pop();
n=n-index;
if(n>=index)

So when the index is 0, n=n-index does nothing, so there is the cause of your infinite loop.

Peverel · 08-06-2011, 07:23 AM

I suggest you trace pop() by putting in a suitable printf(). You might find that it is not push() which is looping.

mscoder · 08-06-2011, 07:24 AM

@johnsfine...the "\" was a stray one added during editing the post...it has nothing to do with the code which showed the prblm in push()...sorry about that

johnsfine · 08-06-2011, 07:29 AM

Quote:

Originally Posted by mscoder

@johnsfine...the "\" was a stray one added during editing the post...it has nothing to do with the code which showed the prblm in push()...sorry about that

Reread my post, above. I was editing it at the time you first read it, so you missed the important part.

johnsfine · 08-06-2011, 07:32 AM

Quote:

Originally Posted by Peverel

I suggest you trace pop() by putting in a suitable printf(). You might find that it is not push() which is looping.

The loop is actually in function(). It is the statement while(top!=-1)
and that loops forever because
if(n>=index)
is true forever in the case that index is zero and n is positive.

mscoder · 08-06-2011, 07:36 AM

Quote:

I suggest you trace pop() by putting in a suitable printf(). You might find that it is not push() which is looping.

thanks..i got the prblm..

...it was pop() indeed that was looping in the very first function call with array index 0...

Peverel · 08-06-2011, 07:37 AM

Johnsfine: exactly so. But I hoped he might find it himself!