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1.8.3.1
gecode
int
linear
post.hpp
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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
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/*
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* Main authors:
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* Christian Schulte <schulte@gecode.org>
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*
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* Copyright:
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* Christian Schulte, 2002
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*
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* Last modified:
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* $Date: 2013-02-14 16:29:11 +0100 (Thu, 14 Feb 2013) $ by $Author: schulte $
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* $Revision: 13292 $
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*
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* This file is part of Gecode, the generic constraint
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* development environment:
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* http://www.gecode.org
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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*/
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#include <algorithm>
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#include <climits>
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namespace
Gecode {
namespace
Int {
namespace
Linear {
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template
<
class
View>
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inline
void
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estimate
(
Term<View>
*
t
,
int
n
,
int
c
,
int
&
l
,
int
&
u
) {
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long
long
int
min
=
c
;
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long
long
int
max
=
c
;
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for
(
int
i
=n;
i
--; ) {
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long
long
int
a
= t[
i
].
a
;
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if
(a > 0) {
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min += a*t[
i
].
x
.min();
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max += a*t[
i
].
x
.max();
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}
else
{
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max += a*t[
i
].
x
.min();
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min += a*t[
i
].
x
.max();
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}
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}
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if
(min <
Limits::min
)
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min =
Limits::min
;
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if
(min >
Limits::max
)
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min =
Limits::max
;
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l =
static_cast<
int
>
(
min
);
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if
(max <
Limits::min
)
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max =
Limits::min
;
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if
(max >
Limits::max
)
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max =
Limits::max
;
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u =
static_cast<
int
>
(
max
);
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}
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template
<
class
View>
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class
TermLess
{
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public
:
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forceinline
bool
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operator ()
(
const
Term<View>
&
a
,
const
Term<View>
&
b
) {
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return
before
(a.
x
,b.
x
);
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}
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};
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inline
int
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gcd
(
int
a
,
int
b
) {
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if
(b > a)
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std::swap(a,b);
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while
(b > 0) {
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int
t
=
b
; b = a %
b
; a =
t
;
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}
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return
a
;
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}
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template
<
class
View>
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inline
bool
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normalize
(
Term<View>
*
t
,
int
&
n
,
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Term<View>
* &t_p,
int
&n_p,
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Term<View>
* &t_n,
int
&n_n,
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int
& g) {
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/*
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* Join coefficients for aliased variables:
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*
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*/
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{
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// Group same variables
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TermLess<View>
tl;
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Support::quicksort<Term<View>,
TermLess<View>
>(
t
,
n
,tl);
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// Join adjacent variables
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int
i
= 0;
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int
j = 0;
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while
(i < n) {
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Limits::check
(t[i].
a
,
"Int::linear"
);
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long
long
int
a = t[
i
].a;
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View
x
= t[
i
].x;
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while
((++i < n) &&
same
(t[i].x,x)) {
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a += t[
i
].a;
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Limits::check
(a,
"Int::linear"
);
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}
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if
(a != 0) {
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t[j].a =
static_cast<
int
>
(
a
); t[j].x =
x
; j++;
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}
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}
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n = j;
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}
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/*
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* Partition into positive/negative coefficents
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*
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*/
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if
(n > 0) {
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int
i
= 0;
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int
j = n-1;
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while
(
true
) {
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while
((t[j].
a
< 0) && (--j >= 0)) ;
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while
((t[i].
a
> 0) && (++i <
n
)) ;
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if
(j <= i)
break
;
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std::swap(t[i],t[j]);
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}
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t_p =
t
; n_p =
i
;
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t_n = t+n_p; n_n = n-n_p;
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}
else
{
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t_p =
t
; n_p = 0;
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t_n =
t
; n_n = 0;
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}
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/*
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* Make all coefficients positive
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*
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*/
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for
(
int
i
=n_n;
i
--; )
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t_n[
i
].
a
= -t_n[
i
].
a
;
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/*
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* Compute greatest common divisor
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*
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*/
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if
((n > 0) && (g > 0)) {
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g = t[0].
a
;
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for
(
int
i
=1; (g > 1) && (
i
< n);
i
++)
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g =
gcd
(t[
i
].
a
,g);
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if
(g > 1)
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for
(
int
i
=n;
i
--; )
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t[
i
].a /= g;
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}
else
{
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g = 1;
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}
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/*
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* Test for unit coefficients only
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*
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*/
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for
(
int
i
=n;
i
--; )
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if
(t[
i
].
a
!= 1)
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return
false
;
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return
true
;
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}
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}}}
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// STATISTICS: int-post
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