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binary_heap.c
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binary_heap.c
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#include "binary_heap.h"
HEAP *init_heap(int num_of_nodes){
HEAP *heap = (HEAP *)malloc(sizeof(HEAP));
heap->heap_node = (HEAP_NODE *)malloc(num_of_nodes * sizeof(HEAP_NODE));
heap->heap_max_size = num_of_nodes;
heap->heap_act_size = 0;
return heap;
}
HEAP_NODE *init_heap_node(int index, int path_cost){
HEAP_NODE *heap_node = (HEAP_NODE *)malloc(sizeof(HEAP_NODE));
heap_node->index = index;
heap_node->value = path_cost;
return heap_node;
}
void print_heap(HEAP *heap){
printf("----- Printing heap -----\n");
printf("Number of heap nodes: %d and min is: %d\n", heap->heap_act_size, heap->heap_node[0].value);
for (int i = 0; i < heap->heap_act_size; i++)
printf("%d ", heap->heap_node[i].value);
printf("\n\n");
}
void swap_heap_nodes(HEAP_NODE *h1, HEAP_NODE *h2){
HEAP_NODE temp = *h1;
*h1 = *h2;
*h2 = temp;
}
HEAP_NODE *find_parent(HEAP *heap, int index){
return &heap->heap_node[((index - 1) / 2)];
}
/* reordering and cleaning heap in way of min heap rules */
HEAP *clean_in_heap(HEAP *heap, int i){
HEAP_NODE *parent;
while(i != 0 && heap->heap_node[((i - 1) / 2)].value > heap->heap_node[i].value){
/* Vymenim ich v poli */
swap_heap_nodes(&heap->heap_node[i], &heap->heap_node[((i - 1) / 2)]);
i = (i - 1) / 2;
}
return heap;
}
/* fn for change cost which already is for smaller one */
HEAP *change_for_cheaper_cost(HEAP *heap, int index, int new_path_cost){
int i;
for (i = 0; i < heap->heap_act_size; i++){
if(heap->heap_node[i].index == index){
heap->heap_node[i].value = new_path_cost;
heap = clean_in_heap(heap, i);
return heap;
}
}
printf("change_for_cheaper_cost - nieco je zle lebo som ho nenasiel v halde\n");
}
HEAP *insert_heap_node(HEAP *heap, int index, int path_cost){
HEAP_NODE *heap_node = init_heap_node(index, path_cost);
/* resolution statement, checking max heap size */
if(heap->heap_act_size >= heap->heap_max_size){
printf("No success insert to heap - ochrana proti preteceniu\n");
return heap;
}
int act_index = heap->heap_act_size;
/* vlozim dany heap_node do pola */
heap->heap_node[act_index] = *heap_node;
heap = clean_in_heap(heap, act_index);
heap->heap_act_size++;
return heap;
}
int get_path_index_of_min(HEAP *heap){
return heap->heap_node[0].index;
}
HEAP *change_value_heap_node(HEAP *heap, int index, int new_value){
heap->heap_node[index].value = new_value;
heap = clean_in_heap(heap, index);
return heap;
}
void heapifyTtB(HEAP *heap, int index){
HEAP_NODE *left_child, *right_child;
int left, right, helper;
left = 2 * index + 1;
right = 2 * index + 2;
left_child = &heap->heap_node[left];
right_child = &heap->heap_node[right];
/**
* left and right parent as well are optionall (have a bigger cost),
* choose with smaller cost between tham and replace with child
*/
if((left < heap->heap_act_size && heap->heap_node[index].value > left_child->value) &&
(right < index && heap->heap_node[index].value > right_child->value)){
swap_heap_nodes(&heap->heap_node[index], left_child->value < right_child->value
? &heap->heap_node[left]
: &heap->heap_node[right]);
heapifyTtB(heap, left_child->value < right_child->value
? left
: right);
}
/**
* left parent have a bigger cost, replace with child
*/
if(left < heap->heap_act_size && heap->heap_node[index].value > left_child->value){
swap_heap_nodes(&heap->heap_node[index], &heap->heap_node[left]);
heapifyTtB(heap, left);
}
/**
* right parent have a bigger cost, replace with child
*/
if(right < heap->heap_act_size && heap->heap_node[index].value > right_child->value){
swap_heap_nodes(&heap->heap_node[index], &heap->heap_node[right]);
heapifyTtB(heap, right);
}
}
/* vyberie najmensi cost z haldy (teda root) a pop-ne ho, nalsedne uprace haldu */
HEAP *push_and_pop_min(HEAP *heap, int *path_index_of_min){
*path_index_of_min = get_path_index_of_min(heap);
if(heap->heap_act_size <= 0){
free(heap);
return NULL;
}
if (heap->heap_act_size == 1){
heap->heap_act_size--;
return heap;
}
heap->heap_act_size--;
heap->heap_node[0] = heap->heap_node[heap->heap_act_size];
heapifyTtB(heap, 0);
return heap;
}