81 lines
2.2 KiB
C
81 lines
2.2 KiB
C
#include "priorityqueue.h"
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#include "heap.h"
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#include "types/status.h"
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void heapify(struct priority_queue_t *queue, size_t i)
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{
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if(i * 2 + 1 >= queue->size)
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{
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return;
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}
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else if(queue->heap[i * 2 + 1].priority <= queue->heap[i].priority
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&& queue->heap[i * 2 + 1].priority <= queue->heap[i * 2 + 2].priority)
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{
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struct priority_queue_node_t buffer = queue->heap[i];
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queue->heap[i] = queue->heap[i * 2 + 1];
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queue->heap[i * 2 + 1] = buffer;
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heapify(queue, i * 2 + 1);
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}
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else if(queue->heap[i * 2 + 2].priority <= queue->heap[i].priority
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&& queue->heap[i * 2 + 2].priority <= queue->heap[i * 2 + 1].priority)
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{
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struct priority_queue_node_t buffer = queue->heap[i];
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queue->heap[i] = queue->heap[i * 2 + 2];
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queue->heap[i * 2 + 2] = buffer;
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heapify(queue, i * 2 + 2);
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}
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}
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int construct_priority_queue(struct priority_queue_t *queue, int capacity)
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{
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queue->heap = kmalloc(sizeof(struct priority_queue_node_t) * capacity);
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if(queue->heap == NULL)
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{
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return S_OUT_OF_MEMORY;
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}
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queue->capacity = capacity;
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queue->size = 0;
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return S_OK;
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}
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void *extract_min(struct priority_queue_t *queue)
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{
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if(queue->size == 0)
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return NULL;
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queue->size--;
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void *value = queue->heap[0].value;
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queue->heap[0] = queue->heap[queue->size];
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heapify(queue, 0);
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return value;
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}
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int queue_insert(struct priority_queue_t *queue, void *value, int priority)
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{
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if(queue->size == queue->capacity)
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return S_OUT_OF_MEMORY;
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size_t i = queue->size;
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queue->size++;
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while(i > 0 && queue->heap[(i - 1) / 2].priority > priority)
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{
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queue->heap[i] = queue->heap[(i - 1) / 2];
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i = (i - 1) / 2;
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}
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queue->heap[i].priority = priority;
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queue->heap[i].value = value;
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return S_OK;
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}
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int queue_remove(struct priority_queue_t *queue, void *value)
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{
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for(size_t i = 0; i < queue->size; i++)
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{
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if(queue->heap[i].value == value)
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{
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queue->size--;
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queue->heap[i] = queue->heap[queue->size];
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heapify(queue, i);
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return S_OK;
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}
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}
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return S_OUT_OF_BOUNDS;
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} |