source: trunk/sources/ALGLIB/tsort.cs @ 2636

/*************************************************************************
Copyright 2008 by Sergey Bochkanov (ALGLIB project).

>>> SOURCE LICENSE >>>
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 (www.fsf.org); either version 2 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.

A copy of the GNU General Public License is available at
http://www.fsf.org/licensing/licenses

>>> END OF LICENSE >>>
*************************************************************************/

using System;

namespace alglib
{
    public class tsort
    {
        public static void tagsort(ref double[] a,
            int n,
            ref int[] p1,
            ref int[] p2)
        {
            int i = 0;
            int j = 0;
            int k = 0;
            int t = 0;
            double tmp = 0;
            int tmpi = 0;
            int[] pv = new int[0];
            int[] vp = new int[0];
            int lv = 0;
            int lp = 0;
            int rv = 0;
            int rp = 0;

            
            //
            // Special cases
            //
            if( n<=0 )
            {
                return;
            }
            if( n==1 )
            {
                p1 = new int[0+1];
                p2 = new int[0+1];
                p1[0] = 0;
                p2[0] = 0;
                return;
            }
            
            //
            // General case, N>1: prepare permutations table P1
            //
            p1 = new int[n-1+1];
            for(i=0; i<=n-1; i++)
            {
                p1[i] = i;
            }
            
            //
            // General case, N>1: sort, update P1
            //
            tagsortfasti(ref a, ref p1, n);
            
            //
            // General case, N>1: fill permutations table P2
            //
            // To fill P2 we maintain two arrays:
            // * PV, Position(Value). PV[i] contains position of I-th key at the moment
            // * VP, Value(Position). VP[i] contains key which has position I at the moment
            //
            // At each step we making permutation of two items:
            //   Left, which is given by position/value pair LP/LV
            //   and Right, which is given by RP/RV
            // and updating PV[] and VP[] correspondingly.
            //
            pv = new int[n-1+1];
            vp = new int[n-1+1];
            p2 = new int[n-1+1];
            for(i=0; i<=n-1; i++)
            {
                pv[i] = i;
                vp[i] = i;
            }
            for(i=0; i<=n-1; i++)
            {
                
                //
                // calculate LP, LV, RP, RV
                //
                lp = i;
                lv = vp[lp];
                rv = p1[i];
                rp = pv[rv];
                
                //
                // Fill P2
                //
                p2[i] = rp;
                
                //
                // update PV and VP
                //
                vp[lp] = rv;
                vp[rp] = lv;
                pv[lv] = rp;
                pv[rv] = lp;
            }
        }


        public static void tagsortfasti(ref double[] a,
            ref int[] b,
            int n)
        {
            int i = 0;
            int j = 0;
            int k = 0;
            int t = 0;
            double tmp = 0;
            int tmpi = 0;

            
            //
            // Special cases
            //
            if( n<=1 )
            {
                return;
            }
            
            //
            // General case, N>1: sort, update B
            //
            i = 2;
            do
            {
                t = i;
                while( t!=1 )
                {
                    k = t/2;
                    if( (double)(a[k-1])>=(double)(a[t-1]) )
                    {
                        t = 1;
                    }
                    else
                    {
                        tmp = a[k-1];
                        a[k-1] = a[t-1];
                        a[t-1] = tmp;
                        tmpi = b[k-1];
                        b[k-1] = b[t-1];
                        b[t-1] = tmpi;
                        t = k;
                    }
                }
                i = i+1;
            }
            while( i<=n );
            i = n-1;
            do
            {
                tmp = a[i];
                a[i] = a[0];
                a[0] = tmp;
                tmpi = b[i];
                b[i] = b[0];
                b[0] = tmpi;
                t = 1;
                while( t!=0 )
                {
                    k = 2*t;
                    if( k>i )
                    {
                        t = 0;
                    }
                    else
                    {
                        if( k<i )
                        {
                            if( (double)(a[k])>(double)(a[k-1]) )
                            {
                                k = k+1;
                            }
                        }
                        if( (double)(a[t-1])>=(double)(a[k-1]) )
                        {
                            t = 0;
                        }
                        else
                        {
                            tmp = a[k-1];
                            a[k-1] = a[t-1];
                            a[t-1] = tmp;
                            tmpi = b[k-1];
                            b[k-1] = b[t-1];
                            b[t-1] = tmpi;
                            t = k;
                        }
                    }
                }
                i = i-1;
            }
            while( i>=1 );
        }


        public static void tagsortfastr(ref double[] a,
            ref double[] b,
            int n)
        {
            int i = 0;
            int j = 0;
            int k = 0;
            int t = 0;
            double tmp = 0;
            double tmpr = 0;

            
            //
            // Special cases
            //
            if( n<=1 )
            {
                return;
            }
            
            //
            // General case, N>1: sort, update B
            //
            i = 2;
            do
            {
                t = i;
                while( t!=1 )
                {
                    k = t/2;
                    if( (double)(a[k-1])>=(double)(a[t-1]) )
                    {
                        t = 1;
                    }
                    else
                    {
                        tmp = a[k-1];
                        a[k-1] = a[t-1];
                        a[t-1] = tmp;
                        tmpr = b[k-1];
                        b[k-1] = b[t-1];
                        b[t-1] = tmpr;
                        t = k;
                    }
                }
                i = i+1;
            }
            while( i<=n );
            i = n-1;
            do
            {
                tmp = a[i];
                a[i] = a[0];
                a[0] = tmp;
                tmpr = b[i];
                b[i] = b[0];
                b[0] = tmpr;
                t = 1;
                while( t!=0 )
                {
                    k = 2*t;
                    if( k>i )
                    {
                        t = 0;
                    }
                    else
                    {
                        if( k<i )
                        {
                            if( (double)(a[k])>(double)(a[k-1]) )
                            {
                                k = k+1;
                            }
                        }
                        if( (double)(a[t-1])>=(double)(a[k-1]) )
                        {
                            t = 0;
                        }
                        else
                        {
                            tmp = a[k-1];
                            a[k-1] = a[t-1];
                            a[t-1] = tmp;
                            tmpr = b[k-1];
                            b[k-1] = b[t-1];
                            b[t-1] = tmpr;
                            t = k;
                        }
                    }
                }
                i = i-1;
            }
            while( i>=1 );
        }


        public static void tagsortfast(ref double[] a,
            int n)
        {
            int i = 0;
            int j = 0;
            int k = 0;
            int t = 0;
            double tmp = 0;
            double tmpr = 0;

            
            //
            // Special cases
            //
            if( n<=1 )
            {
                return;
            }
            
            //
            // General case, N>1: sort, update B
            //
            i = 2;
            do
            {
                t = i;
                while( t!=1 )
                {
                    k = t/2;
                    if( (double)(a[k-1])>=(double)(a[t-1]) )
                    {
                        t = 1;
                    }
                    else
                    {
                        tmp = a[k-1];
                        a[k-1] = a[t-1];
                        a[t-1] = tmp;
                        t = k;
                    }
                }
                i = i+1;
            }
            while( i<=n );
            i = n-1;
            do
            {
                tmp = a[i];
                a[i] = a[0];
                a[0] = tmp;
                t = 1;
                while( t!=0 )
                {
                    k = 2*t;
                    if( k>i )
                    {
                        t = 0;
                    }
                    else
                    {
                        if( k<i )
                        {
                            if( (double)(a[k])>(double)(a[k-1]) )
                            {
                                k = k+1;
                            }
                        }
                        if( (double)(a[t-1])>=(double)(a[k-1]) )
                        {
                            t = 0;
                        }
                        else
                        {
                            tmp = a[k-1];
                            a[k-1] = a[t-1];
                            a[t-1] = tmp;
                            t = k;
                        }
                    }
                }
                i = i-1;
            }
            while( i>=1 );
        }
    }
}