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LA_library/qsort.h

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/*
LA: linear algebra C++ interface library
Copyright (C) 2008 Jiri Pittner <jiri.pittner@jh-inst.cas.cz> or <jiri@pittnerovi.com>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _QSORT_H
#define _QSORT_H
//quicksort, returns parity of the permutation
//
namespace LA {
template<typename INDEX, typename COMPAR>
int genqsort(INDEX l, INDEX r,COMPAR (*cmp)(const INDEX, const INDEX), void (*swap)(const INDEX,const INDEX))
{
INDEX i,j,piv;
int parity=0;
if(r<=l) return parity; //1 element
if(cmp(r,l)<0) {parity^=1; swap(l,r);}
if(r-l==1) return parity; //2 elements and preparation for median
piv= l+(r-l)/2; //pivoting by median of 3 - safer
if(cmp(piv,l)<0) {parity^=1; swap(l,piv);} //and change the pivot element implicitly
if(cmp(r,piv)<0) {parity^=1; swap(r,piv);} //and change the pivot element implicitly
if(r-l==2) return parity; //in the case of 3 elements we are finished too
//general case , l-th r-th already processed
i=l+1; j=r-1;
do{
//important sharp inequality - stops at sentinel element for efficiency
// this is inefficient if all keys are equal - unnecessary n log n swaps are done, but we assume that it is atypical input
while(cmp(i++,piv)<0);
i--;
while(cmp(j--,piv)>0);
j++;
if(i<j)
{
// swap and keep track of position of pivoting element
parity^=1; swap(i,j);
if(i==piv) piv=j; else if(j==piv) piv=i;
}
if(i<=j) {i++; j--;}
}while(i<=j);
if(j-l < r-i) //because of the stack in bad case process first the shorter subarray
{if(l<j) parity ^=genqsort(l,j,cmp,swap); if(i<r) parity ^=genqsort(i,r,cmp,swap);}
else
{if(i<r) parity ^=genqsort(i,r,cmp,swap); if(l<j) parity ^=genqsort(l,j,cmp,swap);}
return parity;
}
//for SORTABLE classes which provide LA_sort_traits<SORTABLE,INDEX,type>::compare and swap member functions
//this allows to use it in general templates also for complex elements, for which comparison falls back to error
template<int type, typename SORTABLE, typename INDEX, typename PERMINDEX>
int memqsort(SORTABLE &object, PERMINDEX *perm, INDEX l, INDEX r)
{
INDEX i,j,piv;
int parity=0;
if(r<=l) return parity; //1 element
if(LA_sort_traits<SORTABLE,INDEX,type>::compare(object,l,r)) {parity^=1; object.swap(l,r); if(perm) {PERMINDEX tmp=perm[l]; perm[l]=perm[r]; perm[r]=tmp;}}
if(r-l==1) return parity; //2 elements and preparation for median
piv= l+(r-l)/2; //pivoting by median of 3 - safer
if(LA_sort_traits<SORTABLE,INDEX,type>::compare(object,l,piv)) {parity^=1; object.swap(l,piv); if(perm) {PERMINDEX tmp=perm[l]; perm[l]=perm[piv]; perm[piv]=tmp;}} //and change the pivot element implicitly
if(LA_sort_traits<SORTABLE,INDEX,type>::compare(object,piv,r)) {parity^=1; object.swap(r,piv); if(perm) {PERMINDEX tmp=perm[r]; perm[r]=perm[piv]; perm[piv]=tmp;}} //and change the pivot element implicitly
if(r-l==2) return parity; //in the case of 3 elements we are finished too
//general case , l-th r-th already processed
i=l+1; j=r-1;
do{
//important sharp inequality - stops at sentinel element for efficiency
// this is inefficient if all keys are equal - unnecessary n log n swaps are done, but we assume that it is atypical input
while(LA_sort_traits<SORTABLE,INDEX,type>::compare(object,piv,i++));
i--;
while(LA_sort_traits<SORTABLE,INDEX,type>::compare(object,j--,piv));
j++;
if(i<j)
{
// swap and keep track of position of pivoting element
parity^=1; object.swap(i,j); if(perm) {PERMINDEX tmp=perm[i]; perm[i]=perm[j]; perm[j]=tmp;}
if(i==piv) piv=j; else if(j==piv) piv=i;
}
if(i<=j) {i++; j--;}
}while(i<=j);
if(j-l < r-i) //because of the stack in bad case process first the shorter subarray
{if(l<j) parity ^=memqsort<type,SORTABLE,INDEX,PERMINDEX>(object,perm,l,j); if(i<r) parity ^=memqsort<type,SORTABLE,INDEX,PERMINDEX>(object,perm,i,r);}
else
{if(i<r) parity ^=memqsort<type,SORTABLE,INDEX,PERMINDEX>(object,perm,i,r); if(l<j) parity ^=memqsort<type,SORTABLE,INDEX,PERMINDEX>(object,perm,l,j);}
return parity;
}
//stabilized version of quicksort employing auxiliary key of the original position
template<int type, typename SORTABLE, typename INDEX, typename PERMINDEX>
int memqsortaux(SORTABLE &object, PERMINDEX *perm, INDEX l, INDEX r, INDEX *aux)
{
INDEX i,j,piv;
int parity=0;
if(r<=l) return parity; //1 element
if(LA_sort_traits<SORTABLE,INDEX,type>::comparestable(object,l,r,aux)) {parity^=1; object.swap(l,r); {INDEX tmp=aux[l]; aux[l]=aux[r]; aux[r]=tmp;} if(perm) {PERMINDEX tmp=perm[l]; perm[l]=perm[r]; perm[r]=tmp;}}
if(r-l==1) return parity; //2 elements and preparation for median
piv= l+(r-l)/2; //pivoting by median of 3 - safer
if(LA_sort_traits<SORTABLE,INDEX,type>::comparestable(object,l,piv,aux)) {parity^=1; object.swap(l,piv); {INDEX tmp=aux[l]; aux[l]=aux[piv]; aux[piv]=tmp;} if(perm) {PERMINDEX tmp=perm[l]; perm[l]=perm[piv]; perm[piv]=tmp;}} //and change the pivot element implicitly
if(LA_sort_traits<SORTABLE,INDEX,type>::comparestable(object,piv,r,aux)) {parity^=1; object.swap(r,piv); {INDEX tmp=aux[r]; aux[r]=aux[piv]; aux[piv]=tmp;} if(perm) {PERMINDEX tmp=perm[r]; perm[r]=perm[piv]; perm[piv]=tmp;}} //and change the pivot element implicitly
if(r-l==2) return parity; //in the case of 3 elements we are finished too
//general case , l-th r-th already processed
i=l+1; j=r-1;
do{
//important sharp inequality - stops at sentinel element for efficiency
// this is inefficient if all keys are equal - unnecessary n log n swaps are done, but we assume that it is atypical input
while(LA_sort_traits<SORTABLE,INDEX,type>::comparestable(object,piv,i++,aux));
i--;
while(LA_sort_traits<SORTABLE,INDEX,type>::comparestable(object,j--,piv,aux));
j++;
if(i<j)
{
// swap and keep track of position of pivoting element
parity^=1;
object.swap(i,j);
{INDEX tmp =aux[i]; aux[i]=aux[j]; aux[j]=tmp;}
if(perm) {PERMINDEX tmp=perm[i]; perm[i]=perm[j]; perm[j]=tmp;}
if(i==piv) piv=j; else if(j==piv) piv=i;
}
if(i<=j) {i++; j--;}
}while(i<=j);
if(j-l < r-i) //because of the stack in bad case process first the shorter subarray
{if(l<j) parity ^=memqsortaux<type,SORTABLE,INDEX,PERMINDEX>(object,perm,l,j,aux); if(i<r) parity ^=memqsortaux<type,SORTABLE,INDEX,PERMINDEX>(object,perm,i,r,aux);}
else
{if(i<r) parity ^=memqsortaux<type,SORTABLE,INDEX,PERMINDEX>(object,perm,i,r,aux); if(l<j) parity ^=memqsortaux<type,SORTABLE,INDEX,PERMINDEX>(object,perm,l,j,aux);}
return parity;
}
template<int type, typename SORTABLE, typename INDEX, typename PERMINDEX>
int memqsortstable(SORTABLE &object, PERMINDEX *perm, INDEX l, INDEX r)
{
if(r<=l) return 0; //1 element
INDEX *aux= new INDEX[r-l+1];
if(aux==NULL) laerror("allocation failed in memqsortstable");
INDEX *auxshifted = aux-l;
for(INDEX i=l; i<=r; ++i) auxshifted[i]=i;
int parity=memqsortaux<type,SORTABLE,INDEX,PERMINDEX>(object,perm,l,r,auxshifted);
delete[] aux;
return parity;
}
template<typename S, typename PERMINDEX>
int ptrqsortup(S *l, S *r, PERMINDEX *perm=NULL)
{
S *i,*j,*piv;
int parity=0;
if(r-l<=0) return parity; //1 element
if(*l > *r) {parity^=1; {S tmp; tmp=*l; *l= *r; *r=tmp;} if(perm) {PERMINDEX tmp=*perm; *perm=perm[r-l]; perm[r-l]=tmp;}}
if(r-l==1) return parity; //2 elements and preparation for median
piv= l+(r-l)/2; //pivoting by median of 3 - safer
if(*l>*piv) {parity^=1; {S tmp; tmp=*l; *l=*piv; *piv=tmp;} if(perm) {PERMINDEX tmp= *perm; *perm=perm[piv-l]; perm[piv-l]=tmp;}} //and change the pivot element implicitly
if(*piv>*r) {parity^=1; {S tmp; tmp=*r; *r=*piv; *piv=tmp;} if(perm) {PERMINDEX tmp=perm[r-l]; perm[r-l]=perm[piv-l]; perm[piv-l]=tmp;}} //and change the pivot element implicitly
if(r-l==2) return parity; //in the case of 3 elements we are finished too
//general case , l-th r-th already processed
i=l+1; j=r-1;
do{
//important sharp inequality - stops at sentinel element for efficiency
// this is inefficient if all keys are equal - unnecessary n log n swaps are done, but we assume that it is atypical input
while(*piv > *i++);
i--;
while(*j-- > *piv);
j++;
if(i<j)
{
// swap and keep track of position of pivoting element
parity^=1; {S tmp; tmp=*i; *i=*j; *j=tmp;} if(perm) {PERMINDEX tmp=perm[i-l]; perm[i-l]=perm[j-l]; perm[j-l]=tmp;}
if(i==piv) piv=j; else if(j==piv) piv=i;
}
if(i<=j) {i++; j--;}
}while(i<=j);
if(j-l < r-i) //because of the stack in bad case process first the shorter subarray
{if(l<j) parity ^=ptrqsortup(l,j,perm); if(i<r) parity ^=ptrqsortup(i,r,perm+(i-l));}
else
{if(i<r) parity ^=ptrqsortup(i,r,perm+(i-l)); if(l<j) parity ^=ptrqsortup(l,j,perm);}
return parity;
}
template<typename S, typename PERMINDEX>
int ptrqsortdown(S *l, S *r, PERMINDEX *perm=NULL)
{
S *i,*j,*piv;
int parity=0;
if(r-l<=0) return parity; //1 element
if(*l < *r) {parity^=1; {S tmp; tmp=*l; *l= *r; *r=tmp;} if(perm) {PERMINDEX tmp=*perm; *perm=perm[r-l]; perm[r-l]=tmp;}}
if(r-l==1) return parity; //2 elements and preparation for median
piv= l+(r-l)/2; //pivoting by median of 3 - safer
if(*l<*piv) {parity^=1; {S tmp; tmp=*l; *l=*piv; *piv=tmp;} if(perm) {PERMINDEX tmp= *perm; *perm=perm[piv-l]; perm[piv-l]=tmp;}} //and change the pivot element implicitly
if(*piv<*r) {parity^=1; {S tmp; tmp=*r; *r=*piv; *piv=tmp;} if(perm) {PERMINDEX tmp=perm[r-l]; perm[r-l]=perm[piv-l]; perm[piv-l]=tmp;}} //and change the pivot element implicitly
if(r-l==2) return parity; //in the case of 3 elements we are finished too
//general case , l-th r-th already processed
i=l+1; j=r-1;
do{
//important sharp inequality - stops at sentinel element for efficiency
// this is inefficient if all keys are equal - unnecessary n log n swaps are done, but we assume that it is atypical input
while(*piv < *i++);
i--;
while(*j-- < *piv);
j++;
if(i<j)
{
// swap and keep track of position of pivoting element
parity^=1; {S tmp; tmp=*i; *i=*j; *j=tmp;} if(perm) {PERMINDEX tmp=perm[i-l]; perm[i-l]=perm[j-l]; perm[j-l]=tmp;}
if(i==piv) piv=j; else if(j==piv) piv=i;
}
if(i<=j) {i++; j--;}
}while(i<=j);
if(j-l < r-i) //because of the stack in bad case process first the shorter subarray
{if(l<j) parity ^=ptrqsortdown(l,j,perm); if(i<r) parity ^=ptrqsortdown(i,r,perm+(i-l));}
else
{if(i<r) parity ^=ptrqsortdown(i,r,perm+(i-l)); if(l<j) parity ^=ptrqsortdown(l,j,perm);}
return parity;
}
//heapsort
//DATA must have assignmend and comparison operators implemented
template<typename INDEX, typename DATA>
void myheapsort(INDEX n, DATA *ra,int typ=1)
{
INDEX l,j,ir,i;
DATA rra;
ra--; //below indexed from 1
l=(n >> 1)+1;
ir=n;
for (;;) {
if (l > 1) {
rra=ra[--l];
} else {
rra=ra[ir];
ra[ir]=ra[1];
if (--ir == 1) {
ra[1]=rra;
return;
}
}
i=l;
j=l << 1;
while (j <= ir) {
if (j < ir && (typ>0?ra[j] < ra[j+1]:ra[j]>ra[j+1])) ++j;
if (typ>0?rra < ra[j]:rra>ra[j]) {
ra[i]=ra[j];
j += (i=j);
}
else j=ir+1;
}
ra[i]=rra;
}
}
//network up-sorting templates
//more elegant would be a double template with N and partial specialization, but this is not allowed in current C++ for non-member functions
//
#define CONDSWAP(i,j) if(data[i]>data[j]) {T tmp=data[i]; data[i]=data[j]; data[j]=tmp; parity^=1;}
template<typename T>
inline int netsort_0(T *data) {return 0;}
template<typename T>
inline int netsort_1(T *data) {return 0;}
template<typename T>
inline int netsort_2(T *data)
{
int parity=0;
CONDSWAP(0,1);
return parity;
}
template<typename T>
inline int netsort_3(T *data)
{
int parity=0;
CONDSWAP(0,2);
CONDSWAP(0,1);
CONDSWAP(1,2);
return parity;
}
template<typename T>
inline int netsort_4(T *data)
{
int parity=0;
CONDSWAP(0,2);
CONDSWAP(1,3);
CONDSWAP(0,1);
CONDSWAP(2,3);
CONDSWAP(1,2);
return parity;
}
template<typename T>
inline int netsort_5(T *data)
{
int parity=0;
CONDSWAP(0,3);
CONDSWAP(1,4);
CONDSWAP(0,2);
CONDSWAP(1,3);
CONDSWAP(0,1);
CONDSWAP(2,4);
CONDSWAP(1,2);
CONDSWAP(3,4);
CONDSWAP(2,3);
return parity;
}
template<typename T>
inline int netsort_6(T *data)
{
int parity=0;
CONDSWAP(0,5);
CONDSWAP(1,3);
CONDSWAP(2,4);
CONDSWAP(1,2);
CONDSWAP(3,4);
CONDSWAP(0,3);
CONDSWAP(2,5);
CONDSWAP(0,1);
CONDSWAP(2,3);
CONDSWAP(4,5);
CONDSWAP(1,2);
CONDSWAP(3,4);
return parity;
}
#undef CONDSWAP
template<typename T>
int netsort(const int n, T *data)
{
if(n<0) laerror("negative n in netsort");
switch(n)
{
case 0:
case 1:
return 0;
break;
case 2:
return netsort_2(data);
break;
case 3:
return netsort_3(data);
break;
case 4:
return netsort_4(data);
break;
case 5:
return netsort_5(data);
break;
case 6:
return netsort_6(data);
break;
default:
return ptrqsortup<T,int>(data,data+n-1);
break;
}
return 0;
}
}//namespace
#endif
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