/*
* 合并斐波那契堆的根链表中左右相同度数的树
*/
static void fib_heap_consolidate(FibHeap *heap)
{
int i, d, D;
FibNode *x, *y, *tmp;
fib_heap_cons_make(heap);//开辟哈希所用空间
D = heap->maxDegree + 1;
for (i = 0; i < D; i++)
heap->cons[i] = NULL;
// 合并相同度的根节点，使每个度数的树唯一
while (heap->min != NULL)
{
x = fib_heap_remove_min(heap); // 取出堆中的最小树(最小节点所在的树)
d = x->degree; // 获取最小树的度数
// heap->cons[d] != NULL，意味着有两棵树(x和y)的"度数"相同。
while (heap->cons[d] != NULL)
{
y = heap->cons[d]; // y是"与x的度数相同的树"
if (x->key > y->key) // 保证x的键值比y小
{
tmp = x;
x = y;
y = tmp;
}
fib_heap_link(heap, y, x); // 将y链接到x中
heap->cons[d] = NULL;
d++;
}
heap->cons[d] = x;
}
heap->min = NULL;
// 将heap->cons中的结点重新加到根表中
for (i=0; i<D; i++)
{
if (heap->cons[i] != NULL)
{
if (heap->min == NULL)
heap->min = heap->cons[i];
else
{
fib_node_add(heap->cons[i], heap->min);
if ((heap->cons[i])->key < heap->min->key)
heap->min = heap->cons[i];
}
}
}
}
/**
* Transform the root list into a list of binonmial heaps.
* It makes the amortized cost so good for a secuence of mixed insert() and deleteMin() calls.
* Cost: O(log n)
* Pre: this fib_heap has at least 1 element.
* Post: list of binomial heaps
**/
void fib_heap::consolidate()
{
const int max_bin_heaps = 1.5 * (log2(n) + 1) ; //1.5*log n
node_t* aux_array[max_bin_heaps];
//Init array:
for (int i = 0; i<max_bin_heaps; ++i) {
aux_array[i] = nullptr;
}
node_t *aux1, *aux2; //correspondence with MAR notes x <=> aux1 & y <=> aux2
D(std::cerr << "Debug: consolidate loop starts" << std::endl);
//We've gotta go over every node in the root list
while (root_list != nullptr) {
aux1 = root_list;
remove_from_list(root_list,aux1);
//Make aux1 an unitary circular list (link to itself only)
aux1->right = aux1;
aux1->left = aux1;
//Inside this while, we make sure we are creating only one bin heap of every degree
while (aux_array[aux1->degree] != nullptr) {
D(std::cerr << "bin heap of degree " << aux1->degree << " already taken by " << aux_array[aux1->degree]->key << std::endl);
D(std::cerr << "consolidate loop" << std::endl << std::endl);
aux2 = aux_array[aux1->degree]; //Another node with the same degree as aux1
//if aux1 is greater, it swaps them so that aux1 is always <= aux2
if (aux1->key > aux2->key) {
swap(aux1,aux2);
}
aux_array[aux1->degree] = nullptr;
fib_heap_link(aux2,aux1);
}
aux_array[aux1->degree] = aux1;
}
//Now, we restore the heap and the min pointer
for (int i = 0; i<max_bin_heaps; ++i) {
node_t *x = aux_array[i];
if (x != nullptr) {
if (this->isEmpty()) {
root_list = x;
} else {
concatenate_circular_lists(root_list,x);
if (x->key < min->key)
min = x;
}
}
}
D(std::cerr << "Debug: consolidate ok" << std::endl);
D(std::cout << *this << std::endl);
}