1. Stack and Queues Stack implementation using Array
Stack implementation using Linked List
Queue implementation using Array
Queue implementation using Linked List
Convert Infix Exp into Postfix
Evaluate Postfix Expression

2. Stack using Array Push 10 Push 20 Push 30 Pop Push 50 4 3 30 2 Top 20
Top
Top = -1 50

3. const int max=100; void main ( ) { int DATA [max ] ,Top= -1, c ; do clrscr( ); cout << “1.Push\n2.Pop\n3.Show\nExit Any other number\n”; cin>>c ; switch ( c ) case 1 : push ( DATA , Top) ; break ; case 2 : pop ( DATA , Top) ; break ; case 3 : show ( DATA , Top) ; break ; } } while(c>=1 && c<= 3);

4. void push ( int Num [ ] , int & Top ) { int item ; //Check overflow condition if ( Top == max – 1 ) cout<<“Overflow “; } else cout << “Enter Item To Push into the stack\n”; cin >> item; Top = Top +1; Num [ Top ] =item; cout<<“Item Inserted “;

5. void pop ( int Num [ ] , int & Top ) { //Check underflow condition if ( Top == – 1 ) cout<<“underflow “; } else cout << Num[ Top ]<<“is to be deleted \n“; Top = Top -1; cout<<“Item deleted “;

6. void show ( int Num [ ] , int Top ) { //Check underflow condition if ( Top == – 1 ) cout<<“underflow “; } else cout << Num[ Top ]<<“Top \n“; for ( i= Top -1; i > = 0 ; i - - ) cout<< Num [ i ] << endl ;

7. char * msg [ ] = {“over flow”, “under flow”};
class Stack {
int Top ;
int DATA [10];
void error (int e_num)
{ cout<< msg [e_num ] ; }
public:
void init () { Top = -1 ; }
void Push ( int );
void Pop ( ); };
Define Push which accept an item and insert into stack.
Define Pop to delete an item from stack.
( Use error ( ) function for underflow and overflow condition

8. void push ( int Num [ ] , int & Top ) { int item ; //Check overflow condition if ( Top == max – 1 ) cout<<“Overflow “; } else cout << “Enter Item”; cin >> item; Top = Top +1; Num [ Top ] =item; cout<<“Item Inserted “;
void Stack :: push ( int item ) {
int item ;
//Check overflow condition
if ( Top == 10 – 1 )
error(0); }
else
cout << “Enter Item”;
cin >> item;
Top = Top +1;
DATA [ Top ] =item;
cout<<“Item Inserted “;

9. void Stack :: pop ( ) { //Check underflow condition if ( Top == – 1 ) cout<<“underflow “; } else cout << DATA[ Top ]<<“is to be deleted \n“; Top = Top -1; cout<<“Item deleted “;

10. Linked List
Linked list is a data structure in which an element of list point to another element of list. It is implemented with the help of pointers and self referential structure. Each element ( also called node ) contain two fields : Information part and Pointer.
Pointer
struct Student {
int RollNo;
char Name[20] ;
Student * link ; }
InfoPart
Link
InfoPart
Link
InfoPart
Link
Null

11. Stack Implementation Using Linked List
Stack is a data structure in which top pointer point to top element of stack. It is implemented with the help of pointers and self referential structure. Each element ( also called node ) contain two fields : Information part and Pointer.
Top
struct Student {
int RollNo;
char Name[20] ;
Student * link ; }
InfoPart
Link
InfoPart
Link
InfoPart
Link
Null

12. cout << “1.Push\n2.Pop\n3.Show\nExit Any other number\n”;
struct Student {
int RollNo;
char Name[20] ;
Student * link ;
} ;
student *Top = NULL;
void main ( )
int c ; do
clrscr( );
cout << “1.Push\n2.Pop\n3.Show\nExit Any other number\n”;
cin>>c ;
switch ( c )
case 1 : push ( ) ; break ;
case 2 : pop ( ) ; break ;
case 3 : show ( ) ; break ; }
} while(c>=1 && c<= 3);

13. Top
void push ( ) { //create node Student *ptr ; ptr = new Student ; if ( ptr == NULL ) // checking overflow { cout << “Overflow “ ; return ; } //assigning Values cout << “Enter RollNo “ ; cin >> ptr -> RollNo; cout << “Enter Name “ ; gets( ptr -> Name ) ; ptr - > link =NULL; // Insert Node (Element) if ( Top = = NULL ) { Top = ptr ; } else ptr - > link =Top ; top = ptr ; }
Null
InfoPart
Link
Ptr
Null
Top
InfoPart
Link
InfoPart
Link
InfoPart
Link
Null
Null
Ptr

14. Top
void Pop ( ) { student *ptr ; if ( Top = = NULL ) { cout<<“Underflow “ ; } else ptr=top; cout<<ptr->name<<“being deleted”; Top=Top - > link ; delete ptr ; }
Null
Top
InfoPart
Link
InfoPart
Link
Null
Ptr

15. void Display ( ) { student
void Display ( ) { student *ptr ; if ( Top = = NULL ) { cout<<“Underflow “ ; } else ptr=top; while (ptr!=NULL) cout<<“Name”<<ptr->Name<<“,”<<“RollNo”<<ptr->RollNo; ptr=ptr - > link ; }

16. Convert Infix expression into Postfix expression
Suppose expression X in infix notation and X is to be converted in equivalent postfix expression Y.
Put X inside “(“ and “) “
Scan X from Left to Right and follow steps 3 to 6 until X is empty.
If an operand is encountered , add it to Y.
If an operator is encountered , then
Repeatedly pop from STACK and add to Y each operator on the top of the stack which has the same precedence as or higher precedence than operator.
Push operator to stack
If a right “)” is encountered , then
Repeatedly pop from STACK and add to Y each operator on the top of the stack until left “(” is encountered .
Remove left “(“ from stack.
If a left “)” is encountered , then Push to stack
End

17. Convert Infix into Postfix
Exp :- (( X + Y ) / ( Z * Y ) –R) No
Ele
Action
Stack
Postfix Exp Y 1 (
Push 2
( , ( 3 X
Add to Y 4 +
( , ( , + 5 Y XY 6 )
Pop + and add, Remove (
XY + 7 /
( , / 8
( , / ,( 9 Z
Add
( , / , (
XY+ Z 10 *
( , / , ( , * 11
( , / , ( , *
XY+ZY 12
Pop * ,Add to Exp , Remove (
( , /
XY+ZY * 13 -
( , -
XY+ZY * / 14 R
( , -
XY+ZY * / R 15
Pop - ,Add to Exp ,Remove (
Empty
XY+ZY * / R -

18. Evaluation of Postfix expression
Suppose expression X in postfix expression.
Scan X from Left to Right and follow steps 2 to 4.
If an operand is encountered , push on to stack.
If an operator is encountered , then
Pop two operand from stack (pop one operand for unary operator )
Evaluate expresseion formed by (Operand1) Operator (Operand2).
Push the result on to stack
If X is empty (no more element) , then pop the resul from stack
End

19. Evaluation of Postfix Exp
Ele
Action
Stack
Calculation 1 10
Push 2 3
10 , 3 *
Pop 10 , 3 / cal / push Result 30
10*3=30 4 7
30,7 5
30,7,1 6 -
Pop 7, 1 / cal / push Result
30, 6
7-1=6
Pop 30 , 6 / cal / push Result
180
30*6=180 8 23
180,23 9 +
Pop 180 , 23 / cal / push Result
203
180+23
Ans :- 203