UNIT VI. STACKS AND QUEUES

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1 UNIT VI. STACKS AND QUEUES Syllabus: /* */ Stack: Definition: "Stack is an ordered collection of data elements having similar data type, insersion and deletion of elemnts in a stack takesplace from only one end and is called as top." Features of Stack: 1) Stack is a linear data structure 2) Insersion and deletion of elemnts in a stack takesplace from only one end and is called as top. 3) It is not allowed to access any elemnt of stack randomly 4) Operations possible on stack are push,pop,retrieve,isempty,isfull,inilialize,overflow,underflow ADT for an Stack: Implementation of stack: 1) Array implementation 2) Link list Implementation Applications of Stack: Following are the applications of stack. 1) Arithmetic Expression conversion from one form to another i.e. a) Convert Infix expression to postfix conversion b) Convert Infix expression to prefix conversion c) Convert Postfix to Infix expression d) Convert Prefix to Infix expression e) Convert Prefix to Postfix expression f) Convert Postfix to prefix 2) Evaluation of arithmetic expressions a) Evaluation of postfix expression b) Evaluation of prefix expression 3) Simulation of stack 4) Impementation of recursion using stack 5) Reversing an string using Stack 6) Converting Decimal to Binary using stack

2 Applications of stack in details: 1) Arithmetic Expression conversion from one form to another i.e. a) Convert Infix expression to postfix conversion: Algorithm to convert Infix expression to postfix conversion: Input : Infix expression Output : Postfix expression Data structures required : Stack, infix,postfix expression Step 1: Start Step 2: Accept infix expression from user. Check it is properly entered or not b) Convert Infix expression to prefix conversion c) Convert Postfix to Infix expression d) Convert Prefix to Infix expression e) Convert Prefix to Postfix expression f) Convert Postfix to prefix Concept of Multi Stack: Queues: Definition: ADT for an Queue: Types of Queues: Applications of Queue: 1) Linear Queue : /* Program : Write a program in c language to implement linear queue using array Programmer: Sandip M.Walunj */ #include<stdio.h> #include<conio.h> #define MAX 100 struct Queue int data[max]; int front; int rear; ; struct Queue Q; void initialize();

3 void Insert(); void Delete(); int isfull(); int isempty(); void Display(); int main() int ch,x; char c; initialize(); do clrscr(); printf("\n\n\t Linear Queue operations"); printf("\n\n\t 1. Insert"); printf("\n\n\t 2. Delete"); printf("\n\n\t 3. Display"); printf("\n\n\t 4. isempty"); printf("\n\n\t 5. isfull"); printf("\n\n\t 6. Exit"); printf("\n\n\t Enter your choice(1,2,3,4,5) : "); gotoxy(40,23); scanf("%d",&ch); switch(ch) case 1: Insert(); case 2: Delete(); case 3: Display(); case 4: x=isempty(); if(x==1) printf("\n\n\t Queue is not empty"); case 5: x=isfull(); if(x==1) printf("\n\n\t Queue is full"); printf("\n\n\t Queue is not full"); case 6:

4 exit(0); printf("\n\n\t Do you want to continue(y/n) : "); c=getche(); while(c=='y' c=='y'); getch(); void initialize() Q.front=-1; Q.rear=-1; int isfull() if(q.rear==max-1) return 1; int isempty() if(q.front==-1) return 1; void Insert() int data; if(isfull()) printf("\n\n\t Queue is full"); if(q.front==-1) Q.front=0; Q.rear = Q.rear + 1; printf("\n\n\t Enter data to insert : "); scanf("%d",&data); Q.data[Q.rear] = data; printf("\n\n\t %d is inserted in queue successfully",data);

5 void Delete() int data; if(isempty()) data = Q.data[Q.front]; if(q.front==q.rear) Q.front=-1; Q.rear=-1; Q.front = Q.front + 1; printf("\n\n\t %d is deleted from queue successfully",data); void Display() int i; if(isempty()) printf("\n\n\t Contents of queue : "); for(i=q.front;i<=q.rear;i++) printf(" %d",q.data[i]); 2) Circular Queue 3) Deque 4) Priority Queue

Linear Data Structure

Linear Data Structure Definition A data structure is said to be linear if its elements form a sequence or a linear list. Examples: Array Linked List Stacks Queues Operations on linear Data Structures Traversal