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  1. #include <stdio.h>
  2. #include <stdlib.h> // For qsort
  3. #define QUEUESIZE 10 // Number of items the Queue can hold
  4. typedef enum { false, true } bool;  // Use #include <stdbool.h> if available
  5.  
  6. typedef struct {
  7.     char name[10];
  8.     int priority;
  9. } Item;
  10.  
  11. Item *templist[QUEUESIZE]; // Used for sorting
  12.  
  13. typedef struct {
  14.     Item *q[QUEUESIZE+1];		// queue container
  15.     int first;                  // index of first element
  16.     int last;                   // index of last element
  17.     int count;                  // number of elements currently in queue
  18. } Queue;
  19.  
  20.  
  21. init_queue(Queue *q) {
  22.     q->first = 0;
  23.     q->last = QUEUESIZE-1;
  24.     q->count = 0;
  25. }
  26.  
  27. int cmpfunc (const void * a, const void * b) {
  28.     // Modify this function to do comparision on structure's other properties
  29.     return ((*(Item**)a)->priority > (*(Item**)b)->priority);
  30. }
  31.  
  32. void enqueue(Queue *q, Item *x){
  33.     if (q->count >= QUEUESIZE) {
  34.         printf("Queue overflow\n");
  35.     } else {
  36.         q->last = (q->last+1) % QUEUESIZE;
  37.         q->q[ q->last ] = x;    
  38.         q->count = q->count + 1;                
  39.     }
  40. }
  41.  
  42. Item *dequeue(Queue *q) {
  43.     Item *x;
  44.  
  45.     if (q->count <= 0) {
  46.         printf("Queue empty\n");
  47.     } else {
  48.         x = q->q[ q->first ];
  49.         q->first = (q->first+1) % QUEUESIZE;
  50.         q->count = q->count - 1;
  51.     }
  52.  
  53.     return(x);
  54. }
  55.  
  56. void enqueue_with_priority(Queue *q, Item *x) {
  57. 	int i, count;
  58. 	enqueue(q, x);
  59. 	count = q->count;
  60. 	for(i=0; i < count; ++i) {
  61. 		templist[i] = dequeue(q);
  62. 	}
  63.     qsort(templist, count, sizeof(Item *), cmpfunc);
  64.     for(i=0; i < count; ++i ) {
  65.     	enqueue(q, templist[i]);
  66.     }
  67.  
  68. }
  69.  
  70. int empty(Queue *q) {
  71.     return q->count <= 0 ? true : false;
  72. }
  73.  
  74.  
  75. int main() {
  76.     Queue item_queue;
  77.     init_queue(&item_queue);
  78.  
  79.     Item apple = {"apple", 10};
  80.     Item ball = {"ball", 2};
  81.     Item onion = {"onion", 8};
  82.  
  83.     enqueue_with_priority(&item_queue, &apple);
  84.     enqueue_with_priority(&item_queue, &ball);
  85.     enqueue_with_priority(&item_queue, &onion);
  86.  
  87.     dequeue(&item_queue);
  88.     dequeue(&item_queue);
  89.     dequeue(&item_queue);
  90.  
  91.     return empty(&item_queue) ? 0 : -1;
  92. }
Success #stdin #stdout 0s 5500KB
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https://ideone.com/M0Glr4
language:
C (gcc 8.3)
created:
2 years ago
visibility:
public

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