82 lines
2.8 KiB
C
82 lines
2.8 KiB
C
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/* List implentation of a partition of consecutive integers.
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Copyright (C) 2000 Free Software Foundation, Inc.
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Contributed by CodeSourcery, LLC.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* This package implements a partition of consecutive integers. The
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elements are partitioned into classes. Each class is represented
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by one of its elements, the canonical element, which is chosen
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arbitrarily from elements in the class. The principal operations
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on a partition are FIND, which takes an element, determines its
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class, and returns the canonical element for that class, and UNION,
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which unites the two classes that contain two given elements into a
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single class.
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The list implementation used here provides constant-time finds. By
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storing the size of each class with the class's canonical element,
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it is able to perform unions over all the classes in the partition
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in O (N log N) time. */
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#ifndef _PARTITION_H
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#define _PARTITION_H
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#ifdef __cplusplus
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extern "C" {
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#endif /* __cplusplus */
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#include <ansidecl.h>
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#include <stdio.h>
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struct partition_elem
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{
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/* The canonical element that represents the class containing this
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element. */
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int class_element;
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/* The next element in this class. Elements in each class form a
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circular list. */
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struct partition_elem* next;
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/* The number of elements in this class. Valid only if this is the
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canonical element for its class. */
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unsigned class_count;
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};
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typedef struct partition_def
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{
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/* The number of elements in this partition. */
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int num_elements;
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/* The elements in the partition. */
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struct partition_elem elements[1];
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} *partition;
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extern partition partition_new PARAMS((int));
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extern void partition_delete PARAMS((partition));
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extern int partition_union PARAMS((partition,
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int,
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int));
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extern void partition_print PARAMS((partition,
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FILE*));
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/* Returns the canonical element corresponding to the class containing
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ELEMENT__ in PARTITION__. */
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#define partition_find(partition__, element__) \
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((partition__)->elements[(element__)].class_element)
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#endif /* _PARTITION_H */
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