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| author | Paul Jungeblut <paul.jungeblut@gmail.com> | 2017-07-29 18:12:01 +0200 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2017-07-29 18:12:01 +0200 |
| commit | fa200ce752674fbfa464536d315c61fdb98d4be9 (patch) | |
| tree | 86adde58f7ff8c73d364f92b97899f4e6c03a4b8 /graph | |
| parent | 7cbca064aefe26f9a4606fbdab938889cb3a182b (diff) | |
| parent | dc068beb30a7f257640178dcd00512ed6594a061 (diff) | |
Merge pull request #28 from mzuenni/master
implemented new bitonic tsp algorithm
Diffstat (limited to 'graph')
| -rw-r--r-- | graph/bitonicTSP.cpp | 39 | ||||
| -rw-r--r-- | graph/graph.tex | 5 |
2 files changed, 28 insertions, 16 deletions
diff --git a/graph/bitonicTSP.cpp b/graph/bitonicTSP.cpp index bf01f9e..f607f2c 100644 --- a/graph/bitonicTSP.cpp +++ b/graph/bitonicTSP.cpp @@ -1,16 +1,29 @@ -// Laufzeit: O(|V|^2) -vector< vector<double> > dp; // Initialisiere mit -1 -vector< vector<double> > dist; // Initialisiere mit Entfernungen zwischen Punkten. -vector<int> lr, rl; // Links-nach-rechts und rechts-nach-links Pfade. -int n; // #Knoten +// Laufzeit: O(n^2) +vector<vector<double>> dist; // Initialisiere mit Entfernungen zwischen Punkten. +vector<vector<double>> dp; +vector<vector<bool>> choice; -// get(0, 0) gibt die Länge der kürzesten bitonischen Route. double get(int p1, int p2) { - int v = max(p1, p2) + 1; - if (v == n - 1) return dist[p1][v] + dist[v][p2]; - if (dp[p1][p2] > -0.5) return dp[p1][p2]; - double tryLR = dist[p1][v] + get(v, p2), tryRl = dist[v][p2] + get(p1, v); - if (tryLR < tryRL) lr.push_back(v); // Baut die Pfade auf. Fügt v zu rl hinzu, falls beide gleich teuer. - else rl.push_back(v); // Änder das, falls nötig. - return min(tryLR, tryRL); + int v = max(p1, p2) + 1; + if (v == dist.size()) return dist[p1][v - 1] + dist[p2][v - 1]; + if (dp[p1][p2] >= 0.0) return dp[p1][p2]; + double tryLR = dist[p1][v] + get(v, p2), tryRL = dist[p2][v] + get(p1, v); + choice[p1][p2] = tryLR < tryRL; + return dp[p1][p2] = min(tryLR, tryRL); +} + +void bitonicTour() { + dp = vector<vector<double>>(dist.size(), vector<double>(dist.size(), -1)); + choice = vector<vector<bool>>(dist.size(), vector<bool>(dist.size())); + get(0, 0); + // return dp[0][0]; // Länger der Tour + vector<int> lr = {0}, rl = {0}; + for (int p1 = 0, p2 = 0, v; (v = max(p1, p2) + 1) < dist.size();) { + if (choice[p1][p2]) { + lr.push_back(v); p1 = v; + } else { + rl.push_back(v); p2 = v; + }} + lr.insert(lr.end(), rl.rbegin(), rl.rend()); + // return lr; // Enthält Knoten 0 zweimal. An erster und letzter Position. } diff --git a/graph/graph.tex b/graph/graph.tex index 937b976..596c0d6 100644 --- a/graph/graph.tex +++ b/graph/graph.tex @@ -37,7 +37,6 @@ Erkennt negative Zyklen. \subsection{Strongly Connected Components (\textsc{Tarjans}-Algorithmus)} \lstinputlisting{graph/scc.cpp} -% TODO (pjungeblut): This has errors for bridges! \subsection{Artikulationspunkte und Brücken} \lstinputlisting{graph/articulationPoints.cpp} @@ -110,6 +109,6 @@ Nochmal ca. Faktor 2 schneller als Ford Fulkerson mit Capacity Scaling. % \subsection{TSP} % \lstinputlisting{graph/TSP.cpp} -% \subsection{Bitonic TSP} -% \lstinputlisting{graph/bitonicTSP.cpp} +\subsection{Bitonic TSP} +\lstinputlisting{graph/bitonicTSP.cpp} |
