| 1 | /**************************************************************************
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| 2 | *
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| 3 | * mgheap.h -- Heap routines
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| 4 | * Copyright (C) 1994 Neil Sharman
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or modify
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| 7 | * it under the terms of the GNU General Public License as published by
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| 8 | * the Free Software Foundation; either version 2 of the License, or
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| 9 | * (at your option) any later version.
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| 10 | *
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| 11 | * This program is distributed in the hope that it will be useful,
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | * GNU General Public License for more details.
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| 15 | *
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| 16 | * You should have received a copy of the GNU General Public License
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| 17 | * along with this program; if not, write to the Free Software
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| 18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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| 19 | *
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| 20 | **************************************************************************/
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| 21 |
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| 22 | /* Care should be taken when using these routines as NO error checking is
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| 23 | * done.
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| 24 | */
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| 25 |
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| 26 |
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| 27 |
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| 28 | /* The heap comparison routine should return
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| 29 | * <0 : If a should be before b
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| 30 | * 0 : If a and b are equal
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| 31 | * >0 : If a should be after b
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| 32 | */
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| 33 | typedef int (*heap_comp) (void *a, void *b);
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| 34 |
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| 35 |
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| 36 | /************************************************************************
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| 37 | *
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| 38 | * NOTE: If you choose to change the comparison function the first thing
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| 39 | * you do after changing the function is call heap_build.
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| 40 | *
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| 41 | */
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| 42 | void heap_build (void *heap, int size, int num, heap_comp hc);
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| 43 |
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| 44 |
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| 45 |
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| 46 | /************************************************************************
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| 47 | *
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| 48 | * NOTE : The heap must be built before heap_sort is called.
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| 49 | * This has the effect of reversing the order of the array.
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| 50 | * e.g. if your comparison function is designed to pull the
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| 51 | * biggest thing off the heap first then the result of
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| 52 | * sorting with this function will be to put the bigest
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| 53 | * thing at the end of the array.
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| 54 | *
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| 55 | */
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| 56 | void heap_sort (void *heap, int size, int num, heap_comp hc);
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| 57 |
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| 58 | /***********************************************************************
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| 59 | *
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| 60 | * NOTE: After deleting the head the heap will be one item shorter.
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| 61 | * The deleted item will be placed at the end of the heap.
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| 62 | *
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| 63 | */
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| 64 | void heap_deletehead (void *heap, int size, int *num, heap_comp hc);
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| 65 |
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| 66 |
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| 67 | /***********************************************************************
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| 68 | *
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| 69 | * If you change the "value" of the root node of the heap then you
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| 70 | * should call this to re-pritorize the heap.
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| 71 | *
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| 72 | */
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| 73 | void heap_changedhead (void *heap, int size, int num, heap_comp hc);
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| 74 |
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| 75 |
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| 76 | /***********************************************************************
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| 77 | *
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| 78 | * This assumes that the item has been added to the end of the
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| 79 | * array that is the heap. But that num has not been changed.
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| 80 | *
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| 81 | */
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| 82 | void heap_additem (void *heap, int size, int *num, heap_comp hc);
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