SINGLE LINKED LIST. Algorithm for allocating memory for the new node

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1 SRI CHANDRASEKHARENDRA SARASWATHI VISWA MAHAVIDYALAYA SCSVMV UNIVERSITY DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING Faculty: S.Gokulakrishnan AP/CSE SINGLE LINKED LIST Aim:- Write a C program to implement single linked list. Algorithm: Algorithm for declaration of structure NODE Struct NODE DATA : Data Field LINK: Link Field (Address of next struct NODE) End Struct Algorithm for allocating memory for the new node GETNODE() Size: integer; newnode:node Step 1: Set SIZE = get the size of the NODE STEP 2: Set NEWNODE = Allocate space in memory for the size of size and return the initial address STEP 3: NEWNODE End GETNODE()

2 Algorithm For Reading The Content For The New Node READNODE(NEWNODE: NODE) STEP 1:Read, NEWNODE DATA STEP 2: Set NEWNODE LINK = NULL STEP 3: End READNODE() Algorithm for CREATELIST () CREATELIST() HEAD, LAST, NEWNODE:NODE STEP1: Set NEWNODE = GETNODE() STEP 2: CALL READNODE(NEWNODE) STEP 3: Set HEAD = NEWNODE STEP 4: Set LAST = NEWNODE STEP 5: If you want to add another NODE proceed otherwise STOP STEP 6: Set NEWNODE = GETNODE() STEP 7: CALL READNODE(NEWNODE) STEP 8: Assign LAST LINK = NEWNODE STEP 9: Assign LAST = LAST LINK STEP 10: Goto STEP 5 END CREATELIST()

3 Algorithm for inserting a node as the first node in the list INSERT_FIRST(HEAD : NODE) NEWNODE:NODE STEP1 : Set NEWNODE = GETNODE() STEP 2: CALL READNODE (NEWNODE) STEP 3: If(HEAD= = NULL) Set HEAD = NEWNODE STEP 4: Assign NEWNODE LINK = HEAD STEP 5: Set HEAD = NEWNODE END INSERT_FIRST() Algorithm for inserting a node as the last node in the list LAST, NEWNODE: NODE STEP 1: Set NEWNODE = GETNODE() STEP 2: CALL READNODE(NEWNODE) STEP 3: If(HEAD = = NULL) Set HEAD = NEWNODE STEP 4: Set LAST = HEAD STEP 5: Repeat While (LAST LINK!= NULL) Assign LAST = LAST LINK [End of While Structure] STEP 6: Assign LAST LINK = NEWNODE END INSERT_LAST()

4 Algorithm for inserting a node at any intermediate position in the list INSERT_MIDDLE (HEAD:NODE) LAST,NEWNODE:NODE CONDITION:DATA of the any one NODE in the LIST for insert STEP 1: Set NEWNODE = GETNODE() STEP 2: CALL READNODE(NEWNODE) STEP 3: If(HEAD = = NULL) Set HEAD = NEWNODE STEP 4: Print, Enter the data of NODE after which the insertion is to be made STEP 5: READ, CONDITION STEP 6: Set LAST = HEAD STEP 7: Repeat While(LAST!= NULL) STEP 8: If (LAST DATA == CONDITION ) Then Else Assign NEWNODE LINK = LAST LINK Assign LAST LINK = NEWNODE Assign LAST=LAST LINK STEP 9: [End of STEP 7 while structure] STEP 10: Print, CONDITION IS NOT AVAILABLE END INSERT_MIDDLE()

5 Algorithm for modifying an existing node MODIFY_NODE(HEAD:NODE) STEP1: If(HEAD==NULL) STEP 2: Print Enter the data of NODE to be modified STEP 3: Read CONDITION STEP 4: Set LAST = HEAD STEP 5: Repeat While(LAST!=NULL) STEP 6: If (LAST DATA == CONDITION) Then Read,LAST DATA Else Assign LAST = LAST LINK STEP 7: [End of STEP 5 while structure] STEP 8: Print, CONDITION IS NOT AVAILABLE END MODIFY_NODE() Algorithm for releasing the memory for the node to be deleted RELEASE_NODE(NEWNODE:NODE) STEP 1: Deallocate the space for the NODE of NEWNODE STEP 2: End RELEASENODE()

6 Algorithm For Deleting The First Node From The List DELETE_FIRST (HEAD:NODE) DELNODE: NODE STEP 1: If(HEAD== NULL) Print List is empty STEP 2: Set DELNODE= head STEP 3: Assign HEAD = HEAD LINK STEP 4: Print Deleted Data is, DELNODE DATA STEP 5: CALL RELEASENODE(DELNODE) END DELETE_FIRST () Algorithm for deleting the last node from the list DELETE_LAST(HEAD:NODE) LAST, PREV, DELNODE:NODE STEP 1: If(HEAD==NULL) Print List is empty STEP 2: If(HEAD LINK = = NULL) Then Set DELNODE = HEAD Set HEAD = NULL Print Deleted Data is, DELNODEDATA

7 STEP 3: Set LAST = HEAD STEP 4: Repeat While (LAST LINK!= NULL) STEP 5: Assign PREV = LAST STEP 6: Assign LAST = LAST LINK STEP 7: [End of STEP 4 While loop] STEP 8: Set DELNODE = LAST STEP 9: PREV LINK = NULL STEP 10: Print Deleted Data is, DELNODE DATA STEP 11: CALL RELEASENODE(DELNODE) END DELETE_LAST() Algorithm for deleting a node at any intermediate position in the list DELETE_MIDDLE(HEAD:NODE) LAST, PREV, DELNODE:NODE DELDATA: Data of the node is the NODE to Delete STEP 1: If(HEAD = = NULL) Print List is Empty STEP 2: Print Enter the DATA of the node in the list for deletion STEP 3: Read DELDATA STEP 4: If( HEAD DATA = = DELDATA) Then Set DELNODE = HEAD

8 Assign HEAD = HEAD LINK Print, Deleted Data is, DELNODE DATA CALL RELEASENODE(DELNODE) STEP 5: Set LAST = HEAD LINK STEP 6: Set PREV= HEAD STEP 7: Repeat While(LAST!= NULL) STEP 8: If( LAST DATA = = DELDATA) Then Set DELNODE = LAST Assign PREV LINK = LAST LINK Print The deleted Data is, DELNODE DATA CALL RELEASENODE(DELNODE) Else Assign LAST = LAST LINK Assign PREV = PREVLINK STEP 9: [End of STEP 7 While Loop] STEP 10: Print DELDATA is not available in the list END DELETE_MIDDLE()

9 Source Code: #include<stdio.h> #include<stdlib.h> #include<conio.h> typedef struct list int idno; struct list *link; node; node *newnode,*lastnode,*head,*midnode,*delnode; void create(); void insertfirst(); void insertlast(); void insertmiddle(); void deletefirst(); void deletelast(); void deletemiddle(); void display(); void main() int i; char ch; clrscr(); head=null; while(1)

10 printf("\nenter the choice: "); printf("\n1.create a list\n2.insert at first\n3.insert at last\n4.insert at middle\n5.delete at first\n6.delete at last\n7.delete at middle\n8.display\n?"); scanf("%d",&i); switch(i) case 1: case 2: case 3: case 4: case 5: case 6: case 7: create(); break; insertfirst(); break; insertlast(); break; insertmiddle(); break; deletefirst(); break; deletelast(); break; deletemiddle();

11 break; case 8: display(); break; default: exit(0); void create() char ch; printf("\n\ncreation\n\n"); do newnode=(node*)malloc(sizeof(node)); printf("\nenter the idno\n"); scanf("\t%d",&newnode->idno); newnode->link=null; if(head==null) head=newnode; else lastnode->link=newnode;

12 lastnode=newnode; printf("\ndo you want to cont...?\n"); ch=getche(); while((ch=='y') (ch=='y')); newnode->link=null; void insertfirst() printf("\n\ninsert AT FIRST\n\n"); newnode=(node*)malloc(sizeof(node)); printf("\nenter the idno :\n"); scanf("%d",&newnode->idno); if(head==null) head=newnode; newnode->link=null; else newnode->link=head; head=newnode; void insertlast()

13 printf("\ninsert AT LAST\n"); lastnode=(node*)malloc(sizeof(node)); printf("\nenter the idno"); scanf("%d",&lastnode->idno); lastnode->link=null; if(head==null) head=lastnode; else newnode=head; while(newnode->link!=null) newnode=newnode->link; newnode->link=lastnode; void insertmiddle() int data; printf("\n\ninsert AT MIDDLE\n\n"); newnode=(node*)malloc(sizeof(node)); printf("\nenter the idno\n"); scanf("%d",&newnode->idno); printf("\nenter the data of node after which insertion to be made\n"); scanf("%d",&data);

14 if(head==null) head=newnode; else lastnode=head; while(lastnode!=null) if(lastnode->idno==data) newnode->link=lastnode->link; lastnode->link=newnode; return; else lastnode=lastnode->link; printf("\ngiven data is not available\n"); void deletefirst() printf("\n\ndeleting AT FIRST\n"); if(head==null)

15 printf("\nlist is empty\n"); return; delnode=head; head=delnode->link; printf("deleted data is %d",delnode->idno); free(delnode); void deletelast() node *prevnode; printf("\n\ndeleting AT LAST\n"); if(head==null) printf("\nlist is empty\n"); return; else delnode=head; while(delnode->link!=null) prevnode=delnode; delnode=delnode->link; if(head==delnode)

16 head=null; printf("\ndeleted node is %d",delnode->idno); free(delnode); prevnode->link=null; printf("\ndeleted data is %d\n",delnode->idno); free(delnode); void deletemiddle() node *prevnode; int data; printf("\n\ndeleting AT MIDDLE\n"); if(head==null) printf("\nlist is empty\n"); return; delnode=head; printf("\nenter the data of node in list for deleting on\n"); scanf("%d",&data); if(head->idno==data) head=head->link;

17 printf("\ndeleted data is %d\n",delnode->idno); free(delnode); return; else delnode=head->link; prevnode=head; while(delnode!=null) if(delnode->idno==data) prevnode->link=delnode->link; printf("\ndeleted data is %d\n", delnode->idno); free(delnode); return; else delnode=delnode->link; prevnode=prevnode->link; printf("\ndata is not found\n");

18 void display() int count=0; printf("\n\ndisplaying\n\n"); if(head==null) printf("\nlist is empty\n"); printf("\n count = %d ",count); return; else newnode=head; for(;newnode!=null;newnode=newnode->link) count=count+1; printf("-->%d",newnode->idno); printf("\t\tcount = %d \n",count);

19 OUTPUT: Enter the choice: 1.Create a list 2.Insert at first 3.Insert at last 4.Insert at middle 5.Delete at first 6.Delete at last 7.Delete at middle 8.Display?1 CREATION Enter the idno 2 Do you want to cont...? y Enter the idno 4 Do you want to cont...? y

20 Enter the idno 6 Do you want to cont...? n Enter the choice: 1.Create a list 2.Insert at first 3.Insert at last 4.Insert at middle 5.Delete at first 6.Delete at last 7.Delete at middle 8.Display?8 DISPLAYING -->2-->4-->6 Count = 3 Enter the choice:?2 INSERT AT FIRST Enter the idno : 1

21 Enter the choice:?3 INSERT AT LAST Enter the idno7 Enter the choice:?4 INSERT AT MIDDLE Enter the idno 3 Enter the data of node after which insertion to be made 2 Enter the choice:?5 DELETING AT FIRST Deleted data is 1 Enter the choice:?6 DELETING AT LAST

22 Deleted data is 7 Enter the choice:?7 DELETING AT MIDDLE Enter the data of node in list for deleting on 3 Deleted data is 3 Enter the choice:?8 DISPLAYING -->2-->4-->6 Count = 3

SRI CHANDRASEKHARENDRA SARASWATHI VISWA MAHAVIDYALAYA (UNIVERSITY ESTABLISHED UNDER SECTION 3 OF UGC ACT 1956) ENATHUR - KANCHIPURAM

SRI CHANDRASEKHARENDRA SARASWATHI VISWA MAHAVIDYALAYA (UNIVERSITY ESTABLISHED UNDER SECTION 3 OF UGC ACT 1956) ENATHUR - KANCHIPURAM 631 561 DATA STRUCTURES LAB LABORATORY RECORD Name : Register. No :