IGNOU BCA 3rd sem Solved Assignment - Write an algorithm for the implementation of Doubly Linked Lists

Write an algorithm for  the implementation of Doubly Linked Lists

Ans

ALGORITHM :-

INSERT:-       

1.if(full list)

1.return=0

2.end if

3.found = Search list(list,pPre,pSucc,datain)

4.if (not found)

1.Allocate(pnew)

2.pNew->data=datain

3.if (pPre is null)

1.pNew ->back=NULL

2.pnew ->fore = list.head

3.list.head=pNew

4.else

1.pNew-> fore = pPre->fore

2.pNew ->back=pPre

5.end if

6.if (pPre ->fore NULL)        

1.list.rear=pNew

7.else

1.pSucc->back=pNew           

8.end if

9.pPre->fore=pNew

10.list.coount=list.count+1

11.return(1)

5.endif

6.return(2)

END algorithm.

DELETE:-

1.if(pdlt NULL)

1.abort (impossible condition in delete double)

2.end if

3.list.count=list.count+1

4.if(pDlt->back ot NULL)

1.pPred=pDlt->back

2.pPred->fore=pDlt->fore

5.else

1.list.head=pDlt->fore

6.endif

7.if (pDlt->fore not NULL)

1.pSucc=pDlt->fore

2.pSucc->back=pDlt->back

8.else

1.list.rear=pDlt->back

9.end if

10.recycle(pDlt)

11.return

End algorithm