fork download
copy 
  1. #include <limits.h>
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4.  
  5. // Node structure representing a single node in the linked
  6. // list
  7. typedef struct Node {
  8.     int data;
  9.     struct Node* next;
  10. } Node;
  11.  
  12. // Function to create a new node
  13. Node* createNode(int new_data)
  14. {
  15.     Node* new_node = (Node*)malloc(sizeof(Node));
  16.     new_node->data = new_data;
  17.     new_node->next = NULL;
  18.     return new_node;
  19. }
  20.  
  21. // Structure to implement queue operations using a linked
  22. // list
  23. typedef struct Queue {
  24.  
  25.     // Pointer to the front and the rear of the linked list
  26.     Node *front, *rear;
  27. } Queue;
  28.  
  29. // Function to create a queue
  30. Queue* createQueue()
  31. {
  32.     Queue* q = (Queue*)malloc(sizeof(Queue));
  33.     q->front = q->rear = NULL;
  34.     return q;
  35. }
  36.  
  37. // Function to check if the queue is empty
  38. int isEmpty(Queue* q)
  39. {
  40.  
  41.     // If the front and rear are null, then the queue is
  42.     // empty, otherwise it's not
  43.     if (q->front == NULL && q->rear == NULL) {
  44.         return 1;
  45.     }
  46.     return 0;
  47. }
  48.  
  49. // Function to add an element to the queue
  50. void enqueue(Queue* q, int new_data)
  51. {
  52.  
  53.     // Create a new linked list node
  54.     Node* new_node = createNode(new_data);
  55.  
  56.     // If queue is empty, the new node is both the front
  57.     // and rear
  58.     if (q->rear == NULL) {
  59.         q->front = q->rear = new_node;
  60.         return;
  61.     }
  62.  
  63.     // Add the new node at the end of the queue and
  64.     // change rear
  65.     q->rear->next = new_node;
  66.     q->rear = new_node;
  67. }
  68.  
  69. // Function to remove an element from the queue
  70. void dequeue(Queue* q)
  71. {
  72.  
  73.     // If queue is empty, return
  74.     if (isEmpty(q)) {
  75.         printf("Queue Underflow\n");
  76.         return;
  77.     }
  78.  
  79.     // Store previous front and move front one node
  80.     // ahead
  81.     Node* temp = q->front;
  82.     q->front = q->front->next;
  83.  
  84.     // If front becomes null, then change rear also
  85.     // to null
  86.     if (q->front == NULL)
  87.         q->rear = NULL;
  88.  
  89.     // Deallocate memory of the old front node
  90.     free(temp);
  91. }
  92.  
  93. // Function to get the front element of the queue
  94. int getFront(Queue* q)
  95. {
  96.  
  97.     // Checking if the queue is empty
  98.     if (isEmpty(q)) {
  99.         printf("Queue is empty\n");
  100.         return INT_MIN;
  101.     }
  102.     return q->front->data;
  103. }
  104.  
  105. // Function to get the rear element of the queue
  106. int getRear(Queue* q)
  107. {
  108.  
  109.     // Checking if the queue is empty
  110.     if (isEmpty(q)) {
  111.         printf("Queue is empty\n");
  112.         return INT_MIN;
  113.     }
  114.     return q->rear->data;
  115. }
  116.  
  117. // Driver code
  118. int main()
  119. {
  120.     Queue* q = createQueue();
  121.  
  122.     // Enqueue elements into the queue
  123.     enqueue(q, 10);
  124.     enqueue(q, 20);
  125.  
  126.       printf("Queue Front: %d\n", getFront(q));
  127.     printf("Queue Rear: %d\n", getRear(q));
  128.  
  129.     // Dequeue elements from the queue
  130.     dequeue(q);
  131.     dequeue(q);
  132.  
  133.  
  134.     // Enqueue more elements into the queue
  135.     enqueue(q, 30);
  136.     enqueue(q, 40);
  137.     enqueue(q, 50);
  138.  
  139.     // Dequeue an element from the queue
  140.     dequeue(q);
  141.  
  142.     printf("Queue Front: %d\n", getFront(q));
  143.     printf("Queue Rear: %d\n", getRear(q));
  144.     return 0;
  145. }
Success #stdin #stdout 0s 5288KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Queue Front: 10
Queue Rear: 20
Queue Front: 40
Queue Rear: 50
https://ideone.com/p1JE29
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!