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#include "queue.h"
#include <stdlib.h>
static int _queue_resize(queue* q, int new_cap)
{
int* new_queue;
int i;
if (new_cap <= q->cap) {
return 0;
}
if ((new_queue = (int*)malloc(new_cap * sizeof(int))) == NULL) {
return 0;
}
if (q->front <= q->back) {
q->front = q->front + q->cap;
}
for (i = q->back; i < q->front; ++i) {
new_queue[i - q->back] = q->queue[i % q->cap];
}
free(q->queue);
q->queue = new_queue;
q->cap = new_cap;
q->front = q->size;
q->back = 0;
return 1;
}
int queue_init(queue* q, int cap)
{
if (cap < 1) {
return 0;
}
if ((q->queue = (int*)malloc(cap * sizeof(int))) == NULL) {
return 0;
}
q->size = 0;
q->cap = cap;
q->front = 0;
q->back = 0;
return 1;
}
int enqueue(queue* q, int item)
{
if (q->size == q->cap) {
if (!_queue_resize(q, 2 * q->cap)) {
return 0;
}
}
q->queue[q->front++] = item;
q->front %= q->cap;
++q->size;
return 1;
}
int dequeue(queue* q)
{
int ret;
if (q->size == 0) {
return -1;
}
ret = q->queue[q->back++];
q->back %= q->cap;
--q->size;
return ret;
}
void queue_delete(queue* q)
{
free(q->queue);
q->queue = NULL;
q->size = 0;
q->cap = 0;
}
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