The document discusses double linked lists and procedures for manipulating them. It defines a record type for the linked list nodes with ID, next, and prev fields. It presents procedures for inserting a node, deleting a node, and searching for a node in the list. For insertion, it checks if the list is empty before adding the new node in the correct location based on ID. For deletion, it handles removal of first, last, and middle nodes by adjusting the next and prev pointers of neighboring nodes. It assigns a flag variable to indicate success or failure. It provides +15 bonus points for writing a search procedure that returns a pointer to the found node's location and a character flag for the search status.

1. Prog_2 course- 2014
2 bytes team
Kinan keshkeh
IT Engineering-Damascus University
3rd year

2. Double Lists
Data
next
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L_S
Data
next
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Data
prev
prev
next
next
Data
L_E

3. Definition
Type
D_P = ^D_R;
D_R = Record
ID:integer;
next:D_P;
prev:D_P;
end;
var
L_S, L_E : D_P;

4. Double Lists Procedures:
1) Insert a Node
2) Delete a Node
3) Search Node

5. Insert a Node
Data
next
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Data
next
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Data
next
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Data
next
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L_E
Data
next
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L_S
Temp

6. 1)
L_S
Nil
15
next
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Temp
L_E

7. 3
next
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20
next
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15
next
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2)
L_S
S
L_E
Temp

8. 3
next
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20
next
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15
next
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3)
L_S
S
L_E
2
next
prev
Temp

9. 3
next
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20
next
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15
next
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L_S
S
L_E
2
next
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Nil
4)
Temp

10. procedure D_L_Insert ( var L_S, L_E: D_P; KEY:integer);
var
Temp , S : D_P;
Located: Boolean;
begin
new(Temp);
temp^.ID:=KEY;
temp^.next:=nil;
temp^.prev:=nil;
15
next
prev
Temp

11. If L_S=nil then
begin
L_S:=Temp;
L_E:=Temp;
end
Else
begin
S:=L_S;
Located:=False;
while (S<>nil) and (not Located) do
if S^.id < key then
S:=S^.next
else
Located:=True;
Temp^.next:=S;
+2 points

12. If S=L_S then
begin
L_S^.prev:=Temp;
L_S:=Temp;
end
Else if S=nil then
begin
Temp^.prev := L_E;
L_E^.next := Temp;
L_E:=Temp;
end
Else
begin
Temp^.prev := S^.prev;
S^.prev^.next := Temp;
S^.prev := Temp;
end;
end;
end; {procedure}

13. 1)
L_S
Nil
Delete a Node
flag
3
L_E

14. 3
next
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20
next
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15
next
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L_S
L_E
key
3
2)
temp
3
next
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L_S
Nil
temp
L_E
flag
2

15. 3
next
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20
next
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15
next
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L_S
L_E
temp
3)
falg
2
key
20

16. 3
next
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20
next
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15
next
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L_S
L_E
4)
flag
2
key
15
S

17. 3
next
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20
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15
next
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L_S
L_E
Nil
flag
1
key
99
5)
S

18. procedure D_L_Delete ( var L_S,L_E: D_P; KEY:integer; var flag :char);
var
Temp , S:D_P;
begin
If L_S=nil then
flag:=‘3’
Else if KEY =L_S^.id then
begin
Temp:=L_S;
L_S:=L_S^.next; ls^.prev:=nill ;
Dispose(Temp);
flag:=‘2’;
If L_s=nil then
L_E:=nil;
Else
L_s^.prev:=nil;
end

19. Else if KEY = L_E^.id then
begin
Temp:=L_E;
L_E:=L_E^.prev; L_E^.next:=nil; Dispose(Temp);
Flag:=‘2’;
end
Else
begin
S:=L_S;
while (S<>nil) and (S^.id <> KEY ) do
S:=S^.next;
if S=nil then
flag:=‘1’;
else
begin
S^.next^.prev:=S^.prev;
S^.prev^.next:=S^.next; Dispose(S);
flag:=‘ 2 ’;
end;
end;
end; {procedure}

20. Homework:
+15 points
اكتب اجرائية البحث عه عنصر ما في سلسة مترابطة
مه طرفيه :
Search( var L_s, L_E : D_P ; Key:integer;
var p: D_P ; var flag: char);
بحيث تحفظ الاجرائية مؤشر على مكان العنصر المراد,
وتعيد محرف يعبر عه حالة البحث ) فشل-وجد العنصر-
السلسلة فارغة(

21. Group : group link
Mobile phone- Kinan : 0994385748
Facebook account : kinan’s account
2 bytes team