Circular Queue, Double Ended Queue, Priority Queue, Applications of stacks, Applications of queue, Recursion,implementing stack using linked list, implementing queue using linked list,josephus problem, removing negatives values from queue

1. Q) Session10 a)Execute program to remove negative values from list of values by using
queues
Program:
#include <stdio.h>
#include <stdlib.h>
#define MAX 10
int queue[MAX],f=-1,r=-1;
void enq();
void deq();
void display();
void deletenegative();
main()
{
int n,i;
printf("enter the number of elements");
scanf("%d",&n);
for(i=1;i<=n;i++)
enq();
display();
printf("nAfter deleting negative valuesn");
deletenegative();
display();
}
void enq()
{
int val;
if(r==MAX-1) {
printf("Queue full");
return;
}
else if(f == -1 && r == -1)
f=r=0;
else
r=r+1;
printf("enter the data to be enteredn");
scanf("%d",&val);
queue[r]=val;
}
void deq()
{
if(f==-1)
{

2. printf("underflow");
return;
}
if(f ==r)
f=r=-1;
else
f=f+1;
}
void display()
{
int i;
if(f ==-1)
printf("queue emptyn");
else
{
for(i=f; i<=r;i++)
printf("%dt",queue[i]);
}
}
void move(int i)
{
for( ;i<r;i++)
queue[i]=queue[i+1];
}
void deletenegative()
{
int i;
if(f ==-1)
printf("queue emptyn");
else
{
for(i=f; i<=r;)
{
if(queue[i] <0)
{
if(i==f)
{
deq();
i=i+1;
}
else
{

3. move(i);
r=r-1;
i=i-1;
}
}
else
i=i+1;
}
}
}
To see output... See my blog
http://enthusiaststudent.blogspot.in/2017/01/removing-negative-values-in-queues-c.html
Q) 10 bEnqueue, Dequeue and Display operations in Circular Queue using Arrays
#include <stdio.h>
#include <stdlib.h>
#define MAX 5
int cqueue[MAX], front=-1, rear=-1;
void deq();
void enq();
void display();
main()
{
int n,i;
printf("enter the number of elements");
scanf("%d",&n);
for(i=1;i<=n;i++)
enq();
display();
deq();
display();
}
void enq()
{
int val;
if((front == 0 && rear == MAX-1)||(front == rear+1))
{
printf("Queue full");
return;
}
if(front == -1 && rear == -1)
front = rear = 0;
else if(rear == MAX-1)

4. rear== 0;
else
rear=rear+1;
printf("enter the data to be enteredn");
scanf("%d",&val);
cqueue[rear]=val;
}
void deq()
{
if(front == -1 && rear == -1)
{
printf("queue is empty");
return;
}
printf("ndeleted element=%dn ",cqueue[front]);
if(front == rear)
front = rear = -1;
else if(front == MAX-1)
front = 0;
else
front = front+1;
}
void display()
{
int i;
if(front == -1 && rear == -1
{
printf(“queue is empty”);
return;
}
if(front <= rear)
{
for(i=front;i<=rear;i++)
printf("%dt",cqueue[i]);
}
else
{
for(i=front;i<MAX;i++)
printf("%dt",cqueue[i]);
for(i=0;i<=rear;i++)
printf("%dt",cqueue[i]);
}
}
Q11a) Implement Input Restricted and output Restricted DEQUEUE(Double ended
Queue)
#include <stdio.h>
#include <stdlib.h>
#define MAX 100
/*DEQUEUE IS ALWAYS IMPLEMENTED USING CIRCULAR QUEUE*/
int dequeue[MAX],front=-1,rear=-1;

5. void deleteFront();//deq();
void deleteRear();
void insertFront();
void insertRear(); //enq()
void display();
main()
{
int opt1,opt2;
while(1)
{
printf("Press 1. Input Restricted 2. Output Restricted 3. display 4. exitn");
scanf("%d",&opt1);
switch(opt1)
{
case 1:
do{
printf("Press 1. insertRear 2. deleteFront 3. deleteRear
4. Display() 5. Backn");
scanf("%d",&opt2);
switch(opt2)
{
case 1: insertRear();
break;
case 2: deleteFront();
break;
case 3: deleteRear();
break;
case 4: display();
break;
}
}while(opt2>=1 && opt2 <= 4);
break;
case 2:
do{
printf("Press 1. deleteFront 2. insertRear 3. insertFront
4. Display 5. Back n");
scanf("%d",&opt2);
switch(opt2)
{
case 1: deleteFront();
break;
case 2: insertRear();
break;
case 3: insertFront();
break;
case 4: display();
break;
}

6. }while(opt2>=1 && opt2 <= 4);
break;
case 3: display();
break;
case 4: exit(0);
}
}
}
void insertRear() // enq()
{
int val;
if((front == 0 && rear == MAX-1)||(front == rear+1))
{
printf("Queue full");
return;
}
if(front == -1 && rear == -1)
front = rear = 0;
else if(rear == MAX-1)
rear== 0;
else
rear=rear+1;
printf("enter the data to be enteredn");
scanf("%d",&val);
dequeue[rear]=val;
}
void deleteFront() //deq()
{
if(front == -1 && rear == -1)
{
printf("queue is empty");
return;
}
printf("ndeleted element=%dn ",dequeue[front]);
if(front == rear)
front = rear = -1;
else if(front == MAX-1)
front = 0;
else
front = front+1;
}
void insertFront()
{
int val;
if((front == 0 && rear == MAX-1)||(front == rear+1))
{
printf("Queue full");
return;
}

7. if(front == -1 && rear == -1)
front = rear = 0;
else if(front == 0)
front = MAX-1;
else
front=front-1;
printf("enter the data to be enteredn");
scanf("%d",&val);
dequeue[front]=val;
}
void deleteRear()
{
if(front == -1 && rear == -1)
{
printf("queue is empty");
return;
}
printf("ndeleted element=%dn ",dequeue[front]);
if(front == rear)
front = rear = -1;
else if(rear == 0)
rear = MAX-1;
else
rear = rear-1;
}
void display()
{
int i;
if(front == -1 && rear == -1)
{
printf("queue is empty");
return;
}
if(front <= rear)
{
for(i=front;i<=rear;i++)
printf("%dt",dequeue[i]);
}
else
{
for(i=front;i<MAX;i++)
printf("%dt",dequeue[i]);
for(i=0;i<=rear;i++)
printf("%dt",dequeue[i]);
}
}
Q) 12 Program to implement Ascending Priority queue

8. #include<stdio.h>
#include <stdlib.h>
struct node
{
int data,pri;
struct node *next;
};
struct node *head=NULL,*c,*p;
void create();
void display();
void deleteMin();
main()
{
int n,i;
printf("enter the number of elements");
scanf("%d",&n);
for(i=1;i<=n;i++)
create();
display();
deleteMin();
printf("n after deleting one element, the contents of apq are :n");
display();
}
void create()
{
int v,priority;
printf("enter value and priorityn");
scanf("%d%d",&v,&priority);
struct node *newnode = (struct node *)malloc(sizeof(struct node));
newnode->data =v;
newnode->pri=priority;
newnode->next = NULL;
if(head == NULL)
head = newnode;
else if( newnode->pri < head->pri)
{
newnode->next=head;
head=newnode;
}
else
{
c=head;
while(newnode->pri >= c->pri && c->next != NULL)
{
p=c;
c=c->next;
}
if(c->next == NULL && newnode->pri >= c->pri)
c->next=newnode;
else

9. {
p->next = newnode;
newnode->next=c;
}
}
}
void display()
{
if(head == NULL)
printf("list is empty");
else
{
c=head;
while(c != NULL)
{
printf("%d %d->",c->data,c->pri);
c=c->next;
}
}
}
void deleteMin()
{
/* delete the first node as the first node is minimum in ascending priority queue*/
c=head;
head=head->next;
free(c);
}
Session-13 A) What is a recursive solution to summing up a list of numbers? First you
should note that the sum of [2 13 4 25 66 71 82 91]) is equal to 2 + sum of [ 13 4 25 66 71
82 91]
#include <stdio.h>
int sum(int *a,int index,int n)
{
if(index == n)
return 0;
return(a[index]+sum(a,index+1,n));
}
main()
{
int n,i,a[100];
printf("enter size of arrayn");
scanf("%d",&n);
for(i=0;i<n;i++)
scanf("%d",&a[i]);

10. printf("array sum =%d",sum(a,0,n));
}
Session-13b) . Write a recursive function called elfish? that, given a word, tells us if that
word is elfish or not.
#include <stdio.h>
int elfish(char *s,char *b, int i)
{
if(b[i]=='0')
return 1;
int k,flag=0;
for(k=0;s[k]!='0';k++)
{
if(s[k]==b[i])
{
flag=1;
break;
}
}
if(flag == 1)
return elfish(s,b,i+1);
else
return 0;
}
main()
{
char s[100],b[4]="elf";
int result;
printf("enter the stringn");
gets(s);
result=elfish(s,b,0);
if(result ==0)
printf("given string is not elfish");
else
printf("given string is elfish");
}
Session-14a)Write a recursive function to Find the total number of sequences of length
n (using H and T) such that no two Hs are next to each other.
#include <stdio.h>
int total_seq(int n)
{
if(n == 1)
return 2;
if(n ==2)
return 3;
return(total_seq(n-1)+total_seq(n-2));

11. }
main()
{
int n,i;
printf("enter n value");
scanf("%d",&n);
printf("n Total number of sequences = %d",total_seq(n));
}
Session14 b) Given an array of positive numbers, find the maximum sum of a
subsequence with the constraint that no 2 numbers in the sequence should be adjacent
in the array.
#include<stdio.h>
int excl,incl;
/*Function to return max sum such that no two elements are adjacent */
int FindMaxSum(int *a, int index, int n)
{
int temp;
if(index == n)
return incl;
else
{
temp=incl;
if(incl<(excl+a[index]))
incl=excl+a[index];
excl = temp;
return FindMaxSum(a,index+1,n);
}
}
main()
{
int n, a[100],i;
printf(“enter the number of elementsn”);
scanf(“%d”, &n);
printf(“enter array elementsn”);
for(i=0;i<n;i++)
scanf(“%d”, &a[i]);
incl = a[0];
excl = 0;
printf("nMaximum sum of non- adjacent elements= %d n", FindMaxSum(a,1, n));
}
Session-15a)
Infix to postfix conversion
#include<stdio.h>
#include <process.h>

12. #define MAX 50
char stack[MAX];
int top=-1;
int getpriority(char);
void push(char);
char pop();
main()
{
char infix[50],temp,ch,postfix[50];
int i,j=0;
printf("enter the infix expressionn");
scanf("%s",&infix);
for(i=0; infix[i] != '0'; i++)
{
ch=infix[i];
if(ch == '(')
push(ch);
else if(ch == ')')
{
while(stack[top]!='(')
postfix[j++]=pop();
temp=pop();// popping the (
}
else if(isalnum(ch))
postfix[j++]=ch;
else
{
while(getpriority(stack[top])>=getpriority(ch))
postfix[j++]=pop();
push(ch);
}
}
while(top != -1)
postfix[j++]=pop();
postfix[j]='0';
puts(postfix);
}
int getpriority(char ch)
{
if( ch == '*'|| ch == '/'|| ch == '%')
return 2;
else if(ch == '+' || ch == '-')
return 1;
else
return 0;
}
void push(char item)
{
if(top == MAX-1)
{

13. printf("stack is full");
return;
}
top=top+1;
stack[top]=item;
}
char pop()
{
if(top == -1)
{
printf("stack empty");
return;
}
char temp;
temp=stack[top];
top=top-1;
return temp;
}
Evaluating PostFix expression
#include<stdio.h>
#include <process.h>
#include <string.h>
#define MAX 50
char stack[MAX];
int top=-1;
void push(float);
float pop();
void main()
{
char exp[MAX],temp,ch;
int i;
float op1,op2,value;
printf("Enter an expression : ");
gets(exp);
for(i=0;i<strlen(exp);i++)
{
ch=exp[i];
if(isdigit(ch))
push((float)ch-'0');
else
{
op2=pop();
op1=pop();
switch(ch)

14. {
case '+':
value=op1+op2;
break;
case '-':
value=op1-op2;
break;
case '*':
value=op1*op2;
break;
case '/':
value=op1/op2;
break;
case '%':
value=(int)op1%(int)op2;
break;
}
push(value);
}
}
printf("n Result=%f",pop());
}
void push(float item)
{
if(top == MAX-1)
{
printf("stack is full");
return;
}
top=top+1;
stack[top]=item;
}
float pop()
{
if(top == -1)
{
printf("stack empty");
return;
}
float temp;
temp=stack[top];
top=top-1;

15. return temp;
}
15b) symbol Balancing Using Stacks
#include<stdio.h>
#include <process.h>
#include <string.h>
#define MAX 50
char stack[MAX];
int top=-1;
void push(char);
char pop();
void main()
{
char exp[MAX],temp;
int i, flag=1;
printf("Enter an expression : ");
gets(exp);
for(i=0;i<strlen(exp);i++)
{
if(exp[i]=='(' || exp[i]=='{' || exp[i]=='[')
push(exp[i]);
if(exp[i]==')' || exp[i]=='}' || exp[i]==']')
if(top == -1)
{
flag=0; break;
}
else
{
temp=pop();
if(exp[i]==')' && (temp=='{' || temp=='['))
flag=0;
if(exp[i]=='}' && (temp=='(' || temp=='['))
flag=0;
if(exp[i]==']' && (temp=='(' || temp=='{'))
flag=0;
}
}
if(top>=0)
flag=0;
if(flag==1)
printf("n Valid expression");
else
printf("n Invalid expression");

16. }
void push(char item)
{
if(top == MAX-1)
{
printf("stack is full");
return;
}
top=top+1;
stack[top]=item;
}
char pop()
{
if(top == -1)
{
printf("stack empty");
return;
}
char temp;
temp=stack[top];
top=top-1;
return temp;
}
17a) Use Queue data structure to print binary numbers from 1 to n.
1) Create an empty queue of strings
2) Enqueue the first binary number “1” to queue.
3) Now run a loop for generating and printing n Binary Numbers.
a) Dequeue and Print the front of queue.
b) Append “0” at the end of front item and enqueue it.
c) Append “1” at the end of front item and enqueue it.
Input: n=5
Output: 1,10,11,100,101
#include <stdio.h>
#include <string.h>
#define MAX 20
char queue[MAX][MAX],temp[MAX];
int front=-1, rear=-1;
void enq(char *s)
{
if(rear == MAX-1)
{
printf("Queye full");
return;
}
if(front == -1 && rear == -1)
front=rear=0;
else
rear=rear+1;
strcpy(queue[rear],s);
}
char* deq()

17. {
if(front == -1)
printf("stack is empty");
else
{
strcpy(temp,queue[front]);
if(front == rear)
front = rear = -1;
else
front=front+1;
return temp;
}
}
void bin()
{
char temp2[MAX];
strcpy(temp,deq());
printf("Binary numbers = %sn",temp);
strcpy(temp2,temp);
strcat(temp,"0");
enq(temp);
strcat(temp2,"1");
enq(temp2);
}
main()
{
int i;
char temp[2]="1";
enq(temp);
for(i=1;i<=5;i++)
bin();
}
18a) Implementing Stacks using linked list
#include <stdio.h>
#include <stdlib.h>
struct node
{
int data;
struct node *next;
};
struct node *top=NULL,*c,*p;
void push();
void pop();
void display();
main()
{
int opt;
while(1)
{
printf("nPress 1. Pusht 2. Popt3. Display t4. Exit n");
scanf("%d",&opt);
switch(opt)
{
case 1: push();
break;
case 2: pop();
break;
case 3: display();
break;
case 4: exit(0);
}
}

18. }
void push()
{
int val;
printf("nenter a value to insert into stackn");
scanf("%d",&val);
struct node * newnode=malloc(sizeof(struct node));
newnode->data=val;
newnode->next = NULL;
if(top == NULL)
top = newnode;
else
{
newnode->next=top;
top=newnode;
}
}
void pop()
{
if(top == NULL)
{
printf("n Stack is EMPTY..Deletion is not possible");
return;
}
printf("n Deleted element = %dn",top->data);
c=top;
top=top->next;
free(c);
}
void display()
{
if(top == NULL)
{
printf("stack is empty");
return;
}
else
{
for(c=top;c!=NULL;c=c->next)
printf("%dt",c->data);
}
}
18b) Implementing Queues using Linked List
#include <stdio.h>
#include <stdlib.h>
struct node
{
int data;
struct node *next;
};
struct node *f=NULL,*r = NULL,*c;
void enq();
void deq();
void display();
main()
{

19. int opt;
while(1)
{
printf("n Press 1. Enqt 2. Deqt 3. Display t 4. Exitn");
scanf("%d",&opt);
switch(opt)
{
case 1: enq();
break;
case 2: deq();
break;
case 3: display();
break;
case 4: exit(0);
}
}
}
void enq()
{
int val;
printf("enter value to be enqueuedn");
scanf("%d",&val);
struct node *newnode = (struct node *)malloc(sizeof(struct node));
newnode->data=val;
newnode->next=NULL;
if(f == NULL && r == NULL)
f=r=newnode;
else
{
r->next=newnode;
r= newnode;
}
}
void deq()
{
if(f == NULL && r == NULL)
{
printf("queue is empty");
return;
}
if(f == r)
f = r = NULL;
else
{
c=f;
f=f->next;
free(c);
}
}
void display()
{
if(f == NULL && r == NULL)
{
printf("queue is empty");
return;
}
else
{

20. c=f;
while(c != NULL)
{
printf("%dt",c->data);
c=c->next;
}
}
}
Applications of Stack:
Reversing a list
Parentheses checker
Conversion of an infix expression into a postfix expression
Evaluation of a postfix expression
Conversion of an infix expression into a prefix expression
Evaluation of a prefix expression
Recursion
Tower of Hanoi
Applications of Queue:
 Operating systems often maintain a queue of processes that are ready to execute or
that are waiting for a particular event to occur.
 Computer systems must often provide a “holding area” for messages between two
processes, two programs, or even two systems. This holding area is usually called a
“buffer” and is often implemented as a queue.
 .In real life, Call Center phone systems will use Queues, to hold people calling them
in an order, until a service representative is free. We wait in queues to buy pizza, to
enter movie theaters etc, queue data structure help us simulate and analyze such real
world queues.
 Handling of interrupts in real-time systems. The interrupts are handled in the same
order as they arrive, First come first served.
Q)Addition of Two polynomials using linked list algorithm
Let p and q be the two polynomials represented by the linked list.
1. while p and q are not null, repeat step 2.
2. If exponents of the two terms are equal
then if the terms do not cancel then insert the sum of the terms into the sum Polynomial
Advance p
Advance q
Else if the exponent of the first polynomial> exponent of second
Then insert the term from first polynomial into sum polynomial
Advance p
Else insert the term from second polynomial into sum polynomial
Advance q
3. copy the remaining terms from the non empty polynomial into the
sum polynomial.