algorithms in simple data structures..??

Subject: algorithms in simple data structures..?? Thu Mar 18, 2010 10:34 pm

does ny1 hv easier algortihms of push,pop....etc...coz d ones in sumita arora r kinda difficult to understand....???

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To be frank to u brother...those ar the easiest..! trust me..!

Subject: Re: algorithms in simple data structures..?? Thu Mar 18, 2010 10:40 pm

ohk...firstly...im a gal...

well...then...bro if they r d easiest....
cn u try n explain ny 1 of dem...??
id be grateful...

Active member

eh..? sorry.. i didnt bother to chck ur profile..cuz..im..er..anyway.,..sorry..!

I'll explain the Deletion in a Stack - popping.
If we consider an array of max N elemnts. First we initialise the control variable ctr to top.

ctr = top;
and w're printing the element.now there is a vacant pos at the top. as the elements are poped out frm the top. Now we are pulling the second element to th top and the other elements to the positon just aboove them.

Stack[ctr]=Stack[ctr++]

thats all...!!

If u can undrstand this try using the same mode of thought and try to understand the others too.! If u get any doubt juz ask me.

Subject: Re: algorithms in simple data structures..?? Thu Mar 18, 2010 11:04 pm

ohk...dis seems easy...
thx nyway....

n wats d diff btw deletion in a stack(as an array)....n deletion in a stack(as a linkd list)..??

Active member

You know array is contigous...while a linked list is "linked"..! One node's link part referenced to the Data part of the next one. There are no top or bottom in LL..only last and first. So...if we are deleting ANY node, which we cannot do in Stack Array...! In that LIFO principle is followed. Last In First Out...adn if u want to pop out the middle element u have no way but to pop out all the elements above it.!

But in LL, u can delete any node irrespective of its' position and after u delete a node u have to link the node preceding the deleted node to the node succeeding the deleted node.!!

Thats just a simple differece.

Any more? Im going to take my dinner. I'm starving. So.will be back after 15 mts.

bye

Peace..!

Subject: Re: algorithms in simple data structures..?? Thu Mar 18, 2010 11:14 pm

ya...ok...hv ur dinner..
till den ill try to understand it...
thx..!

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Hi..!

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hey guyzz...howzz the preparations for computer going on.......as for me, I'm getting screwed by section C...... algorithms in simple data structures..?? Icon_biggrin

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Quite well...! What are u getting pinned at..??

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linked lists........

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Hey man can u check a program on deque for me ??....the one given in the sample paper...
here it is....on my own logic.....

class chain
{ int ele[];
int cap,front,rear;
chain(int max)
{ cap=max;
front=0;rear=0;
ele=new int[cap];
}
void pushfront(int v)
{ if((front>0)||(front==0&&rear==0))
{ ele[--front]=v;
}
else
{ System.out.println("Full from front");
}
}
int pop()
{ if(front==0&&rear==0)
{ return 999;
}
else
{ ++front;
return(ele[front-1]);
}
}
void pushrear(int v)
{ if(rear==cap-1)
{ System.out.println("Full from rear");
}
else
{ ele[++rear]=v;
}
}
int poprear()
{ if(front==0&&rear==0)
{ return 999;}
else
{ --rear;
return(ele[rear+1]);
}
}
}

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i found a bug in the initial part.

void pushfront(int v)
{ if((front>0)||(front==0&&rear==0))
{ ele[--front]=v;
}

if front = rear = 0 ie one element in deque then ele[-1]would be initialised to v..?

a negative index would cause a runtime exception...

Subject: Re: algorithms in simple data structures..?? Fri Mar 19, 2010 12:00 am

hey wat progs do u think r important...??
r inheritance,recursion,linkd list progs sure to come...??
or wud it be easy like previous years..??? ny idea...???

Active member

ur right....here's a new version of the pushfront()

void pushfront(int v)
{ if(front>0)
{ ele[--front]=v;
}
else if(front==0&&rear==0)
{ ele[0]=v;}
else
{ System.out.println("Full from front");
}
}

Active member

is the pop part okk dude ??
@ sim27:inheritance and recursion are definitely coming...hope the paper's gonna be easy....only time will tell.....

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i really pray that it wud be easy..! but nothng cud be taken for granted. I am not blindly expecting anythng....just hoping that whatever it is...i can do it..!!!

anyway..all the best everybody...!

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gimme a little more time...!! im checkng..!

Active member

the pop part has a little problem....just that it's not popping.....lolzzz...gotta check that out......

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yeah man sure !!!

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dude..tha same part...what happens to the original ele[front] when u push a new one..???

it gets ovr written ... doesnt it..? and still there remains only one element. which contradicts the case that the deque shud get longer as we add elements...

Active member

hey the program's working cool...I just finished checking......actually when I was printing I forgot to take front and rear as the lower and upper limits and was rather printing the whole array out....stupid me !!! algorithms in simple data structures..?? Icon_mad

.....newayzz....lemme know if you find some mistake....cheers !!!....at last it seems I'm getting into 'queues'......

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nawhh it's not getting overwritten...I'm not shifting elements here...I'm just changing the front and rear index...and when the front is full there can't be any addition in the front...that happens in a stack.....this is a deque..isn't it ??

Active member

dude.. the pop part doesnt work because the push part is not correct.. there is only one element all the time in the deque...and also when u r poping u r not printin the value but 999

if(front==0&&rear==0)
{ return 999;

only this part is repeating as there is only one element..and the reason is cited ealier in this post..!

Active member

thre are two types of deque...input controlled and outpput controlled...

the input restricted only allows isertion at one end but deletion at both ends...

but the output restricted allows deletionat one end only and insertion at both ends..!

urs is wich type..?