106 lines
2.3 KiB
C
106 lines
2.3 KiB
C
// WAP to implement Queue using linked list.
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#include<stdio.h>
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#include<stdlib.h>
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struct node
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{
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int data;
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struct node *next;
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};
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struct node *front;
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struct node *rear;
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void insert();
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void delete();
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void display();
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void main ()
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{
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int choice;
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while(choice != 4)
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{
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printf("\n*************************Main Menu*****************************\n");
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printf("\n=================================================================\n");
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printf("\n1.insert an element\n2.Delete an element\n3.Display the queue\n4.Exit\n");
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printf("\nEnter your choice ?");
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scanf("%d",& choice);
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switch(choice)
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{
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case 1:
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insert();
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break;
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case 2:
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delete();
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break;
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case 3:
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display();
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break;
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case 4:
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exit(0);
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break;
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default:
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printf("\nEnter valid choice??\n");
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}
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}
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}
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void insert()
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{
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struct node *ptr;
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int item;
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ptr = (struct node *) malloc (sizeof(struct node));
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if(ptr == NULL)
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{
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printf("\nOVERFLOW\n");
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return;
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}
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else
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{
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printf("\nEnter value?\n");
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scanf("%d",&item);
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ptr -> data = item;
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if(front == NULL)
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{
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front = ptr;
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rear = ptr;
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front -> next = NULL;
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rear -> next = NULL;
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}
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else
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{
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rear -> next = ptr;
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rear = ptr;
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rear->next = NULL;
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}
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}
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}
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void delete ()
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{
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struct node *ptr;
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if(front == NULL)
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{
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printf("\nUNDERFLOW\n");
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return;
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}
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else
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{
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ptr = front;
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front = front -> next;
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free(ptr);
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}
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}
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void display()
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{
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struct node *ptr;
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ptr = front;
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if(front == NULL)
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{
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printf("\nEmpty queue\n");
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}
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else
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{ printf("\nprinting values .....\n");
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while(ptr != NULL)
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{
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printf("\n%d\n",ptr -> data);
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ptr = ptr -> next;
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}
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}
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} |