178 lines
3.7 KiB
C
178 lines
3.7 KiB
C
/*
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* Copyright (c) 2000-2001
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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#include <stdio.h>
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#include "ufind.h"
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#include "assert.h"
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enum uf_type {uf_ecr,uf_link};
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typedef enum uf_type uf_type;
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struct uf_element
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{
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uf_type type;
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int rank;
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void *info;
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struct uf_element *link;
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};
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struct uf_element *new_uf_element(region r, void *info)
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{
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struct uf_element *result;
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result = ralloc(r, struct uf_element);
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result->type = uf_ecr;
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result->rank = 0;
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result->info = info;
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result->link = NULL;
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return result;
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}
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static struct uf_element *find(struct uf_element *e)
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{
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if (e->type == uf_ecr)
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return e;
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else if (e->link->type == uf_link)
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{
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struct uf_element *temp = e->link;
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e->link = e->link->link;
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return find(temp);
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}
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else
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return e->link;
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}
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bool uf_union(struct uf_element *a, struct uf_element *b)
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{
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struct uf_element *e1 = find(a);
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struct uf_element *e2 = find(b);
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if ( e1 == e2 )
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return FALSE;
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else if (e1->rank < e2->rank)
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{
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e1->type = uf_link;
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e1->link = e2;
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return TRUE;
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}
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else if (e1->rank > e2->rank)
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{
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e2->type = uf_link;
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e2->link = e1;
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return TRUE;
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}
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else
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{
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e2->rank++;
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e1->type = uf_link;
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e1->link = e2;
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return TRUE;
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}
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}
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bool uf_unify(combine_fn_ptr combine,
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struct uf_element *a, struct uf_element *b)
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{
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struct uf_element *e1 = find(a);
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struct uf_element *e2 = find(b);
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if ( e1 == e2 )
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return FALSE;
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else if (e1->rank < e2->rank)
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{
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e2->info = combine(e2->info,e1->info);
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e1->type = uf_link;
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e1->link = e2;
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return TRUE;
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}
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else if (e1->rank > e2->rank)
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{
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e1->info = combine(e1->info,e2->info);
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e2->type = uf_link;
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e2->link = e1;
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return TRUE;
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}
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else
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{
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e2->info = combine(e2->info, e1->info);
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e2->rank++;
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e1->type = uf_link;
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e1->link = e2;
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return TRUE;
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}
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}
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void *uf_get_info(struct uf_element *e)
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{
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return find(e)->info;
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}
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bool uf_eq(struct uf_element *e1,struct uf_element *e2)
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{
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return (find(e1) == find(e2));
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}
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void uf_update(struct uf_element *e,uf_info i)
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{
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find(e)->info = i;
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}
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