Delete Node

8/4/2019 Delete Node

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2. Delete Node Algorithm

Saturday 17 September 2011


2/17

The primary difference between insertion and deletion1. Insertion you put something in the list

2. Deletion you remove something from the list

So in insertion if you create a new node pNew to put into the then for deletion you must obviously know which node to remove

so in our algorithm that node is given by pLoc

So difference between insertion and deletion is that in deletion yopLoc and also in insertion you had datain which holds the data to b

into the node but in delelte node we will have dataout :)



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Logic



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Condition 1: Linked list already has few elements



5/17

Lets go back to our friends list :)

Lets say we have to remove rachell from the list because she wants to go to beauty parlour :o

So what you will do?

We know that in this linked listpoints to phoebephoebe points to rachel

rachel points to joeyjoey to monica

and monica to chandler



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So now if we have to remove rachell from the list we have to mphoebe point to joeyand not to rachell :o

So how do we do it?

Lets say rachell is pLoc

And phoebe is pPre

pPre -> link = pLoc -> link

thats all :) :)



7/17

Pointing Pointing

X

So were going to make phoebe point to joey



8/17

WAIT!!!!!!!!!!!!

Something important i totally forgot!!!!whenever you see ->link

it means that pointing to address of next node

so x = pLoc -> link

this meansx will have the value of the adress of pNext

because pNext comes after pLoc

**If this is confusing ask me again and again!



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Condition 2: Linked list has only one element


S f h l k d l l k h


10/17

So if we have a linked list like this

With only head one node and a terminator

Count Head

0 002 X13 001

And we want to delete that node... the logic we use islist.head = pLoc -> link

so list.head will point to whatever pLoc was pointing towhich is the terminator

Count Head

0 001 X

So now our linked list will look like this ^



11/17

Break Down The algorithm :)

Initialisation

Variable decleration++

Main Logic

Finishing

End*As i said before because were deleting count value is decremented

* Here were not actually declaring a variable.. what doing is... since the node we want to remove has somwe have to delete that data and so just the data we

another variable and recycle it in line 21



12/17

1. Initialisation

Again for this algorithm we need1. the linked list

2. the node to be deleted3. the node before the node to be deleted

4. the data in the node to be deleted

So how do we write the linked list?

ref list how do we write pLoc and pPre?

val pLoc val pPre

how do we write for data?

ref dataOut *remember in insert node it was dataIn :P



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2. Variable Decleration

dataOut = pLoc -> data

this means that dataOut variablewill hold the value/data of pLoc

we do this to delete off the data later in

the algorithm in line 21



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3. Main Logic

Hope this is also easy to understan



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4. Finishing

1. Decrement count value by 1 because were removing a node

2. Delete the value stored in dataOut which as you know holds the

value/data that was stored in pLoc which is the node we want to delete :)


5 E d


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5. End

End is same old story :P



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Ok So that was delete node only 5 steps 1 step less than insertn

Hope everything is clear so far princess :)if u have doubts keep asking me :)


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Delete Node