////   This file contains the C++ code from Program 16.19 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C++"//   by Bruno R. Preiss.////   Copyright (c) 1998 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.pads.uwaterloo.ca/Bruno.Preiss/books/opus4/programs/pgm16_19.cpp//Digraph& CriticalPathAnalysis (Digraph& g){    unsigned int const n = g.NumberOfVertices ();    Array<unsigned int> earliestTime (n);    earliestTime [0] = 0;    g.TopologicalOrderTraversal (	EarliestTimeVisitor (g, earliestTime));    Array<unsigned int> latestTime (n);    latestTime [n - 1U] = earliestTime [n - 1U];    g.DepthFirstTraversal (PostOrder (	LatestTimeVisitor (g, latestTime)), g[0]);    DigraphAsLists slackGraph (n);    for (Vertex::Number v = 0; v < n; ++v)	slackGraph.AddVertex (*new Vertex (v));    Iterator& p = g.Edges ();    while (!p.IsDone ()) {	WeightedEdge& edge =	    dynamic_cast<WeightedEdge&> (*p);	Int& weight =	    dynamic_cast<Int&> (edge.Weight ());	Vertex& v0 = edge.V0 ();	Vertex& v1 = edge.V1 ();	unsigned int const slack =	    latestTime [v1] - earliestTime [v0] - weight;	slackGraph.AddEdge (*new WeightedEdge (	    slackGraph [v0], slackGraph [v1], *new Int(slack)));	++p;    }    delete &p;    return DijkstrasAlgorithm (slackGraph, slackGraph [0]);}