public static PointList ClosestPair(PointList inputList)
{
PointList endpoints = inputList.Clone();
List<PointList> vertexChains = new List<PointList>();
while (endpoints.Count > 2)
{
PairOfPoints closestPair = findClosestPair(forEachPair(endpoints).Where(pair => !inSameVertexChain(pair.A, pair.B, vertexChains)));
PointList chainA = findChainWithEndpoint(closestPair.A, vertexChains);
PointList chainB = findChainWithEndpoint(closestPair.B, vertexChains);
if (chainA != null && chainB != null)
{
vertexChains.Remove(chainA);
vertexChains.Remove(chainB);
chainA.Reverse();
vertexChains.Add(new PointList(chainA.Concat(chainB)));
endpoints.Remove(closestPair.A);
endpoints.Remove(closestPair.B);
continue;
}
if (chainB != null)
{
closestPair = closestPair.Invert();
chainA = chainB;
chainB = null;
}
if (chainA != null)
{
chainA.Insert(0, closestPair.B);
endpoints.Remove(closestPair.A);
continue;
}
vertexChains.Add(new PointList(new List<Point>() { closestPair.A, closestPair.B }));
}
if (vertexChains.Count > 1)
throw new ApplicationException("More than one vertex chain was obtained.");
vertexChains[0].Add(vertexChains[0][0]);
return vertexChains[0];
}
private static PointList nearestNeighbor(PointList inputList, Point startingPoint)
{
Point last = startingPoint;
PointList visited = new PointList() { last };
PointList unvisited = inputList.Clone();
unvisited.Remove(last);
while (unvisited.Count > 0)
{
Point next = findClosestPair(unvisited.ConvertAll(p => new PairOfPoints(last, p))).B;
visited.Add(next);
unvisited.Remove(next);
last = next;
}
visited.Add(visited[0]);
return visited;
}