public List <Node> BreadthFirstSearch(Node root)
{
List <Node> PathToSolution = new List <Node>();
List <Node> OpenList = new List <Node>();
List <Node> ClosedList = new List <Node>();
OpenList.Add(root);
bool goalFound = false;
int expanded = 0;
while (OpenList.Count > 0 && !goalFound)
{
Node currentNode = OpenList[0];
ClosedList.Add(currentNode);
OpenList.RemoveAt(0);
currentNode.ExpandMove();
expanded++;
//currentNode.PrintPuzzle();
for (int i = 0; i < currentNode.children.Count; i++)
{
Node currentChild = currentNode.children[i];
if (currentChild.GoalTest())
{
Console.WriteLine("Goal Found. {0} nodes expanded", expanded);
goalFound = true;
// trace path to root node
PathTrace(PathToSolution, currentChild);
}
if (!Contains(OpenList, currentChild) && !Contains(ClosedList, currentChild))
{
OpenList.Add(currentChild);
}
}
}
return(PathToSolution);
}
public List <Node> DepthFirstSearch(Node root)
{
List <Node> PathToSolution = new List <Node>();
Stack <Node> Fringe = new Stack <Node>();
List <Node> ClosedList = new List <Node>();
Fringe.Push(root);
bool goalFound = false;
int expanded = 0;
while (Fringe.Count > 0 && !goalFound)
{
Node currentNode = Fringe.ElementAt(0);
ClosedList.Add(currentNode);
Fringe.Pop();
currentNode.ExpandMove();
expanded++;
for (int i = currentNode.children.Count - 1; i >= 0; i--)
{
Node currentChild = currentNode.children[i];
if (currentChild.GoalTest())
{
Console.WriteLine("Goal Found. {0} nodes expanded", expanded);
goalFound = true;
// trace path to root node
PathTrace(PathToSolution, currentChild);
}
if (!Contains(Fringe, currentChild) && !Contains(ClosedList, currentChild))
{
Fringe.Push(currentChild);
}
}
}
return(PathToSolution);
}
bool limitFound = false; //to check iterative deepening
public List <Node> DepthLimitedSearch(Node root, int depth)
{
List <Node> PathToSolution = new List <Node>();
Stack <Node> Fringe = new Stack <Node>();
List <Node> ClosedList = new List <Node>();
Fringe.Push(root);
bool goalFound = false;
int expanded = 0;
while (Fringe.Count > 0 && !goalFound)
{
Node currentNode = Fringe.ElementAt(0);
ClosedList.Add(currentNode);
Fringe.Pop();
if (expanded < depth)
{
currentNode.depth = expanded;
currentNode.ExpandMove();
expanded++;
}
else
{
if (Fringe.Count != 0)
{
currentNode = Fringe.ElementAt(0);
ClosedList.Add(currentNode);
Fringe.Pop();
currentNode.depth = expanded;
}
if (currentNode.children.Count == 0 && currentNode.depth < depth)
{
currentNode.ExpandMove();
expanded++;
}
}
for (int i = currentNode.children.Count - 1; i >= 0; i--)
{
Node currentChild = currentNode.children[i];
if (currentChild.GoalTest())
{
Console.WriteLine("Goal Found. {0} nodes expanded", expanded);
goalFound = true;
limitFound = true;
// trace path to root node
PathTrace(PathToSolution, currentChild);
}
if (!Contains(Fringe, currentChild) && !Contains(ClosedList, currentChild))
{
Fringe.Push(currentChild);
}
}
}
if (!goalFound)
{
Console.WriteLine("Goal NOT found for {0} depth limit. Try another", depth);
}
return(PathToSolution);
}