SaraP
81 lines
3.0 KiB
C++
81 lines
3.0 KiB
C++
//----------------------------------------------------------------------------
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// EgalTech 2015-2015
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//----------------------------------------------------------------------------
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// File : TwoOpt.cpp Data : 22.12.15 Versione : 1.6l4
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// Contenuto : Miglioramento del percorso spezzandolo in 2 parti e
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// ricollegando con una delle due parti invertite.
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//
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// K Last K Last
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// o o--<- o--o--<-
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// |\/ |
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// |/\ |
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// o o---> o--o--->
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// First K+1 First K+1
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//
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// Modifiche : 22.12.15 DS Creazione modulo.
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//
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//
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//----------------------------------------------------------------------------
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//--------------------------- Include ----------------------------------------
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#include "stdafx.h"
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#include "ShortestPath.h"
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// ----------------------------------------------------------------------------
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long long unsigned
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ShortestPath::TwoOpt( NODE* pPath)
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{
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const int MAX_TRY = 2048 ;
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unsigned nTry = 1 ;
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unsigned nCount = 1 ;
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NODE* pFirst = pPath ;
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do {
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NODE* pLast = pFirst->pPrev ;
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NODE* pKth = pFirst->pNext ;
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do {
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// lunghezza originale dei tratti da scambiare
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unsigned nEXIST = ArcCost( pLast->nPos, pFirst->nPos) +
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ArcCost( pKth->nPos, pKth->pNext->nPos) ;
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// nuova lunghezza dei tratti da scambiare
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unsigned nTEST = ArcCost( pFirst->nPos, pKth->pNext->nPos) +
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ArcCost( pLast->nPos, pKth->nPos) ;
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// lunghezze originali e nuova del tratto intermedio che viene invertito
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for ( NODE* pCurr = pFirst ; pCurr != pKth ; pCurr = pCurr->pNext) {
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nEXIST += ArcCost( pCurr->nPos, pCurr->pNext->nPos) ;
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nTEST += ArcCost( pCurr->pNext->nPos, pCurr->nPos) ;
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}
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// se lo scambio fa risparmiare
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if ( nTEST < nEXIST) {
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// inverto il tratto intermedio
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for ( NODE* pCurr = pFirst ; pCurr != pKth ;) {
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NODE* pSave = pCurr->pNext ;
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pCurr->pNext = pCurr->pPrev ;
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pCurr->pPrev = pSave ;
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pCurr = pSave ;
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}
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// sistemo gli estremi
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pFirst->pNext = pKth->pNext ;
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pKth->pNext->pPrev = pFirst ;
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pKth->pNext = pKth->pPrev ;
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pKth->pPrev = pLast ;
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pLast->pNext = pKth ;
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pFirst = pLast->pNext ;
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pKth = pFirst->pNext ;
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// faccio ripartire il conto
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nCount = 0 ;
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}
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// altrimenti passo al nodo successivo
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else
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pKth = pKth->pNext ;
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} while ( pKth != pLast->pPrev->pPrev && nCount != 0) ;
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if ( nCount != 0)
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pFirst = pFirst->pNext ;
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nCount ++ ;
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nTry ++ ;
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} while ( nCount < m_nNumPnts && nTry < MAX_TRY) ;
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// ricalcolo il costo del percorso
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return TotalCost( pPath) ;
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}
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