78 lines
2.8 KiB
C++
78 lines
2.8 KiB
C++
/**
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* @file minimun_spanning_tree.h
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*/
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#include <vector>
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/**
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* @brief The class MIN_SPAN_TREE calculates the rectilinear minimum spanning tree
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* of a set of points (pads usually having the same net)
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* this class is an abstract class because you must provide the function
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* int GetWeight( int aItem1, int aItem2 )
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* that calculate the distance between 2 items
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* MIN_SPAN_TREE does not know anything about the actual items to link
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* by the tree
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*/
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class MIN_SPAN_TREE
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{
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protected:
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int m_Size; /* The number of nodes in the graph
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*/
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private:
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std::vector<char> inTree; /* inTree[ii] is a flag set to 1 if the node ii
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* is already in the minimum spanning tree; 0 otherwise
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*/
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std::vector<int> linkedTo; /* linkedTo[ii] holds the index of the node ii would have to be
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* linked to in order to get a distance of d[ii]
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* NOTE: linkedTo[0] is the starting point of the tree
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* linkedTo[1] is the first linked point to use
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* ii and linkedTo[ii] are the 2 ends of an edge in the graph
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*/
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std::vector<int> distTo; /* distTo[ii] is the distance between node ii and the minimum spanning
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* tree;
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* this is initially infinity (INT_MAX);
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* if ii is already in the tree, then d[ii] is undefined;
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* this is just a temporary variable. It's not necessary but speeds
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* up execution considerably (by a factor of n)
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*/
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public:
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MIN_SPAN_TREE();
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void MSP_Init( int aNodesCount );
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void BuildTree();
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int GetWhoTo( int aIdx )
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{
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return linkedTo[aIdx];
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}
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int GetDist( int aIdx )
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{
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return distTo[aIdx];
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}
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/**
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* Function GetWeight
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* calculates the weight between 2 items
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* NOTE: The weight between a node and itself should be 0
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* It is virtual pure, you must provide your GetWeight function
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* @param aItem1 = first item
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* @param aItem2 = other item
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* @return the weight between items ( usually the distance )
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*/
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virtual int GetWeight( int aItem1, int aItem2 ) = 0;
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private:
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/**
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* Function updateDistances
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* should be called immediately after target is added to the tree;
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* updates d so that the values are correct (goes through target's
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* neighbours making sure that the distances between them and the tree
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* are indeed minimum)
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* @param target = index of curr item
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*/
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void updateDistances( int aTarget );
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};
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