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93 lines
2.8 KiB
C
93 lines
2.8 KiB
C
// (c) 2010 Thomas Schoebel-Theuer / 1&1 Internet AG
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#ifndef PAIRING_HEAP_H
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#define PAIRING_HEAP_H
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/* Algorithm: see http://en.wikipedia.org/wiki/Pairing_heap
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* This is just an efficient translation from recursive to iterative form.
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*
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* Note: find_min() is so trivial that we don't implement it.
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*/
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/* generic version: KEYDEF is kept separate, allowing you to
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* embed this structure into other container structures already
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* possessing some key (just provide an empty KEYDEF in this case).
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*/
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#define _PAIRING_HEAP_TYPEDEF(KEYTYPE,KEYDEF) \
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\
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struct pairing_heap_##KEYTYPE { \
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KEYDEF \
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struct pairing_heap_##KEYTYPE *next; \
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struct pairing_heap_##KEYTYPE *subheaps; \
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};
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/* less generic version: define the key inside.
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*/
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#define PAIRING_HEAP_TYPEDEF(KEYTYPE) \
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_PAIRING_HEAP_TYPEDEF(KEYTYPE, KEYTYPE key;)
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/* generic methods: allow arbitrary CMP() functions.
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*/
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#define _PAIRING_HEAP_FUNCTIONS(_STATIC,KEYTYPE,CMP) \
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\
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_STATIC \
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struct pairing_heap_##KEYTYPE *_ph_merge_##KEYTYPE(struct pairing_heap_##KEYTYPE *heap1, struct pairing_heap_##KEYTYPE *heap2) \
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{ \
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if (!heap1) \
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return heap2; \
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if (!heap2) \
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return heap1; \
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if (CMP(heap1, heap2) < 0) { \
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heap2->next = heap1->subheaps; \
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heap1->subheaps = heap2; \
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return heap1; \
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} \
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heap1->next = heap2->subheaps; \
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heap2->subheaps = heap1; \
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return heap2; \
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} \
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\
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_STATIC \
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void ph_insert_##KEYTYPE(struct pairing_heap_##KEYTYPE **heap, struct pairing_heap_##KEYTYPE *new) \
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{ \
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new->next = NULL; \
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new->subheaps = NULL; \
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*heap = _ph_merge_##KEYTYPE(*heap, new); \
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} \
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\
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_STATIC \
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void ph_delete_min_##KEYTYPE(struct pairing_heap_##KEYTYPE **heap) \
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{ \
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struct pairing_heap_##KEYTYPE *tmplist = NULL; \
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struct pairing_heap_##KEYTYPE *ptr; \
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struct pairing_heap_##KEYTYPE *next; \
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struct pairing_heap_##KEYTYPE *res; \
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if (!*heap) { \
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return; \
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} \
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for (ptr = (*heap)->subheaps; ptr; ptr = next) { \
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struct pairing_heap_##KEYTYPE *p2 = ptr->next; \
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next = p2; \
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if (p2) { \
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next = p2->next; \
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ptr = _ph_merge_##KEYTYPE(ptr, p2); \
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} \
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ptr->next = tmplist; \
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tmplist = ptr; \
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} \
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res = NULL; \
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for (ptr = tmplist; ptr; ptr = next) { \
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next = ptr->next; \
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res = _ph_merge_##KEYTYPE(res, ptr); \
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} \
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*heap = res; \
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}
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/* some default CMP() function */
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#define PAIRING_HEAP_COMPARE(a,b) ((a)->key < (b)->key ? -1 : ((a)->key > (b)->key ? 1 : 0))
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/* less generic version: use the default CMP() function */
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#define PAIRING_HEAP_FUNCTIONS(_STATIC,KEYTYPE) \
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_PAIRING_HEAP_FUNCTIONS(_STATIC,KEYTYPE,PAIRING_HEAP_COMPARE)
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#endif
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