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SplayPQ.ccP
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1995-02-06
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// This may look like C code, but it is really -*- C++ -*-
/*
Copyright (C) 1988 Free Software Foundation
written by Doug Lea (dl@rocky.oswego.edu)
This file is part of the GNU C++ Library. This library is free
software; you can redistribute it and/or modify it under the terms of
the GNU Library General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version. This library is distributed in the hope
that it will be useful, but WITHOUT ANY WARRANTY; without even the
implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the GNU Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifdef __GNUG__
#pragma implementation
#endif
#include <stream.h>
#include "<T>.SplayPQ.h"
/*
struct to simulate the special `null' node in the Sleater & Tarjan JACM 1985
splay tree algorithms
All routines use a version of their `simple top-down' splay alg. (p 669)
*/
struct _dummySplayNode
{
<T>SplayNode* lt;
<T>SplayNode* rt;
<T>SplayNode* par;
} _dummy_null;
/*
traversal primitives
*/
<T>SplayNode* <T>SplayPQ::leftmost()
{
<T>SplayNode* t = root;
if (t != 0) while (t->lt != 0) t = t->lt;
return t;
}
<T>SplayNode* <T>SplayPQ::rightmost()
{
<T>SplayNode* t = root;
if (t != 0) while (t->rt != 0) t = t->rt;
return t;
}
<T>SplayNode* <T>SplayPQ::succ(<T>SplayNode* t)
{
if (t == 0)
return 0;
if (t->rt != 0)
{
t = t->rt;
while (t->lt != 0) t = t->lt;
return t;
}
else
{
for (;;)
{
if (t->par == 0 || t == t->par->lt)
return t->par;
else
t = t->par;
}
}
}
<T>SplayNode* <T>SplayPQ::pred(<T>SplayNode* t)
{
if (t == 0)
return 0;
else if (t->lt != 0)
{
t = t->lt;
while (t->rt != 0) t = t->rt;
return t;
}
else
{
for (;;)
{
if (t->par == 0 || t == t->par->rt)
return t->par;
else
t = t->par;
}
}
}
Pix <T>SplayPQ::seek(<T&> key)
{
<T>SplayNode* t = root;
if (t == 0)
return 0;
int comp = <T>CMP(key, t->item);
if (comp == 0)
return Pix(t);
<T>SplayNode* dummy = (<T>SplayNode*)(&_dummy_null);
<T>SplayNode* l = dummy;
<T>SplayNode* r = dummy;
dummy->rt = dummy->lt = dummy->par = 0;
while (comp != 0)
{
if (comp > 0)
{
<T>SplayNode* tr = t->rt;
if (tr == 0)
break;
else
{
comp = <T>CMP(key, tr->item);
if (comp <= 0 || tr->rt == 0)
{
l->rt = t; t->par = l;
l = t;
t = tr;
if (comp >= 0)
break;
}
else
{
if ((t->rt = tr->lt) != 0) t->rt->par = t;
tr->lt = t; t->par = tr;
l->rt = tr; tr->par = l;
l = tr;
t = tr->rt;
comp = <T>CMP(key, t->item);
}
}
}
else
{
<T>SplayNode* tl = t->lt;
if (tl == 0)
break;
else
{
comp = <T>CMP(key, tl->item);
if (comp >= 0 || tl->lt == 0)
{
r->lt = t; t->par = r;
r = t;
t = tl;
if (comp <= 0)
break;
}
else
{
if ((t->lt = tl->rt) != 0) t->lt->par = t;
tl->rt = t; t->par = tl;
r->lt = tl; tl->par = r;
r = tl;
t = tl->lt;
comp = <T>CMP(key, t->item);
}
}
}
}
if ((r->lt = t->rt) != 0) r->lt->par = r;
if ((l->rt = t->lt) != 0) l->rt->par = l;
if ((t->lt = dummy->rt) != 0) t->lt->par = t;
if ((t->rt = dummy->lt) != 0) t->rt->par = t;
t->par = 0;
root = t;
return (comp == 0) ? Pix(t) : 0;
}
Pix <T>SplayPQ::enq(<T&> item)
{
++count;
<T>SplayNode* newnode = new <T>SplayNode(item);
<T>SplayNode* t = root;
if (t == 0)
{
root = newnode;
return Pix(root);
}
int comp = <T>CMP(item, t->item);
<T>SplayNode* dummy = (<T>SplayNode*)(&_dummy_null);
<T>SplayNode* l = dummy;
<T>SplayNode* r = dummy;
dummy->rt = dummy->lt = dummy->par = 0;
int done = 0;
while (!done)
{
if (comp >= 0)
{
<T>SplayNode* tr = t->rt;
if (tr == 0)
{
tr = newnode;
comp = 0; done = 1;
}
else
comp = <T>CMP(item, tr->item);
if (comp <= 0)
{
l->rt = t; t->par = l;
l = t;
t = tr;
}
else
{
<T>SplayNode* trr = tr->rt;
if (trr == 0)
{
trr = newnode;
comp = 0; done = 1;
}
else
comp = <T>CMP(item, trr->item);
if ((t->rt = tr->lt) != 0) t->rt->par = t;
tr->lt = t; t->par = tr;
l->rt = tr; tr->par = l;
l = tr;
t = trr;
}
}
else
{
<T>SplayNode* tl = t->lt;
if (tl == 0)
{
tl = newnode;
comp = 0; done = 1;
}
else
comp = <T>CMP(item, tl->item);
if (comp >= 0)
{
r->lt = t; t->par = r;
r = t;
t = tl;
}
else
{
<T>SplayNode* tll = tl->lt;
if (tll == 0)
{
tll = newnode;
comp = 0; done = 1;
}
else
comp = <T>CMP(item, tll->item);
if ((t->lt = tl->rt) != 0) t->lt->par = t;
tl->rt = t; t->par = tl;
r->lt = tl; tl->par = r;
r = tl;
t = tll;
}
}
}
if ((r->lt = t->rt) != 0) r->lt->par = r;
if ((l->rt = t->lt) != 0) l->rt->par = l;
if ((t->lt = dummy->rt) != 0) t->lt->par = t;
if ((t->rt = dummy->lt) != 0) t->rt->par = t;
t->par = 0;
root = t;
return Pix(root);
}
void <T>SplayPQ::del(Pix pix)
{
<T>SplayNode* t = (<T>SplayNode*)pix;
if (t == 0) return;
<T>SplayNode* p = t->par;
--count;
if (t->rt == 0)
{
if (t == root)
{
if ((root = t->lt) != 0) root->par = 0;
}
else if (t == p->lt)
{
if ((p->lt = t->lt) != 0) p->lt->par = p;
}
else
if ((p->rt = t->lt) != 0) p->rt->par = p;
}
else
{
<T>SplayNode* r = t->rt;
<T>SplayNode* l = r->lt;
for(;;)
{
if (l == 0)
{
if (t == root)
{
root = r;
r->par = 0;
}
else if (t == p->lt)
{
p->lt = r;
r->par = p;
}
else
{
p->rt = r;
r->par = p;
}
if ((r->lt = t->lt) != 0) r->lt->par = r;
break;
}
else
{
if ((r->lt = l->rt) != 0) r->lt->par = r;
l->rt = r; r->par = l;
r = l;
l = l->lt;
}
}
}
delete t;
}
<T>& <T>SplayPQ::front()
{
if (root == 0)
error ("min: empty tree\n");
// else
{
<T>SplayNode* t = root;
<T>SplayNode* l = root->lt;
for(;;)
{
if (l == 0)
{
root = t;
root->par = 0;
return root->item;
}
else
{
if ((t->lt = l->rt) != 0) t->lt->par = t;
l->rt = t; t->par = l;
t = l;
l = l->lt;
}
}
}
}
void <T>SplayPQ::del_front()
{
if (root != 0)
{
--count;
<T>SplayNode* t = root;
<T>SplayNode* l = root->lt;
if (l == 0)
{
if ((root = t->rt) != 0) root->par = 0;
delete t;
}
else
{
for(;;)
{
<T>SplayNode* ll = l->lt;
if (ll == 0)
{
if ((t->lt = l->rt) != 0) t->lt->par = t;
delete l;
break;
}
else
{
<T>SplayNode* lll = ll->lt;
if (lll == 0)
{
if ((l->lt = ll->rt) != 0) l->lt->par = l;
delete ll;
break;
}
else
{
t->lt = ll; ll->par = t;
if ((l->lt = ll->rt) != 0) l->lt->par = l;
ll->rt = l; l->par = ll;
t = ll;
l = lll;
}
}
}
}
}
}
<T> <T>SplayPQ::deq()
{
if (root == 0)
error("deq: empty tree");
// else
{
--count;
<T>SplayNode* t = root;
<T>SplayNode* l = root->lt;
if (l == 0)
{
if ((root = t->rt) != 0) root->par = 0;
<T> res = t->item;
delete t;
return res;
}
else
{
for(;;)
{
<T>SplayNode* ll = l->lt;
if (ll == 0)
{
if ((t->lt = l->rt) != 0) t->lt->par = t;
<T> res = l->item;
delete l;
return res;
}
else
{
<T>SplayNode* lll = ll->lt;
if (lll == 0)
{
if ((l->lt = ll->rt) != 0) l->lt->par = l;
<T> res = ll->item;
delete ll;
return res;
}
else
{
t->lt = ll; ll->par = t;
if ((l->lt = ll->rt) != 0) l->lt->par = l;
ll->rt = l; l->par = ll;
t = ll;
l = lll;
}
}
}
}
}
}
void <T>SplayPQ::_kill(<T>SplayNode* t)
{
if (t != 0)
{
_kill(t->lt);
_kill(t->rt);
delete t;
}
}
<T>SplayNode* <T>SplayPQ::_copy(<T>SplayNode* t)
{
if (t != 0)
{
<T>SplayNode* l = _copy(t->lt);
<T>SplayNode* r = _copy(t->rt);
<T>SplayNode* x = new <T>SplayNode(t->item, l, r);
if (l != 0) l->par = x;
if (r != 0) r->par = x;
return x;
}
else
return 0;
}
int <T>SplayPQ::OK()
{
int v = 1;
if (root == 0)
v = count == 0;
else
{
int n = 1;
<T>SplayNode* trail = leftmost();
<T>SplayNode* t = succ(trail);
while (t != 0)
{
++n;
v &= <T>CMP(trail->item, t->item) < 0;
trail = t;
t = succ(t);
}
v &= n == count;
}
if (!v) error("invariant failure");
return v;
}