// optimal cost of -1 represents no solution!
private void TestSolver <TProblemState>(ISearchAlgorithm <TProblemState> solver, IProblem <TProblemState> problem, double optimalCost)
where TProblemState : IProblemState <TProblemState>
{
output.WriteLine(solver.ToString());
var timer = new Stopwatch();
double lastTotalS = 0d;
ulong lastEvals = 0UL;
// https://docs.microsoft.com/en-us/dotnet/api/system.timers.timer?view=netframework-4.7.2
var reportingTimer = new Timer(10_000);
Action reportingHeartbeat = () => {
var currentTotalS = timer.Elapsed.TotalSeconds;
var currentEvals = solver.StatesEvaluated;
var statesPerSecond = (currentEvals - lastEvals) / (currentTotalS - lastTotalS);
output.WriteLine($"evals: {solver.StatesEvaluated:#,0} ms: {timer.Elapsed.TotalMilliseconds} S/s: {statesPerSecond:#,#.###} cost: {solver.MaxCostEvaulated}");
lastTotalS = currentTotalS;
lastEvals = currentEvals;
};
reportingTimer.Elapsed += (Object source, ElapsedEventArgs e) => reportingHeartbeat();
reportingTimer.AutoReset = true;
reportingTimer.Enabled = true;
timer.Start();
var solution = solver.Solve(problem);
timer.Stop();
reportingTimer.Enabled = false;
reportingHeartbeat();
output.WriteLine("Time: {0}", timer.Elapsed);
if (solution == null)
{
Assert.True(optimalCost == -1d, "Found no solution but one should exist.");
}
else
{
var state = problem.GetInitialState();
output.WriteLine("Initial State ----------------");
output.WriteLine(state.ToString());
int i = 0;
double stepCost, totalCost = 0d;
foreach (var move in solution)
{
i++;
(state, stepCost) = problem.ApplyAction(state, move);
totalCost += stepCost;
//output.WriteLine(state.ToString());
}
output.WriteLine("Final State ({0} moves, {1} cost) ----------------", i, totalCost);
output.WriteLine(state.ToString());
Assert.True(problem.IsGoal(state), "Non-goal state claimed to be goal.");
Assert.True(Math.Abs(optimalCost - totalCost) < 1e-8, "Found a non optimal cost: expected = " + optimalCost + "; actual = " + totalCost);
}
}
public IProblemAction[] Solve(IProblem <TState> problem)
{
StatesEvaluated = 0UL;
MaxCostEvaulated = 0;
var openSet = new OpenSet <double, StateCost <TState> >();
var closedSet = new HashSet <TState>();
var cameFrom = new Dictionary <TState, (TState parent, IProblemAction move)>();
var initialState = problem.GetInitialState();
openSet.PushOrImprove(0, new StateCost <TState>(initialState, 0));
cameFrom.Add(initialState, (default(TState), null));
while (!openSet.IsEmpty)
{
var next = openSet.PopMin();
var state = next.State;
var cost = next.Cost;
closedSet.Add(state);
StatesEvaluated++;
MaxCostEvaulated = Math.Max(MaxCostEvaulated, cost);
if (problem.IsGoal(state))
{
return(RebuildSolution(cameFrom, state));
}
foreach (var move in problem.Expand(state))
{
var(successor, stepCost) = problem.ApplyAction(state, move);
if (closedSet.Contains(successor))
{
continue;
}
var wasImprovement =
openSet.PushOrImprove(
cost + stepCost + heuristic(successor),
new StateCost <TState>(successor, cost + stepCost)
);
if (wasImprovement)
{
cameFrom[successor] = (state, move);
}
}
}
return(null);
}
public IProblemAction[] Solve(IProblem <TState> problem)
{
StatesEvaluated = 0UL;
MaxCostEvaulated = 0;
var openSet = new OpenSet <double, StateCost <TState> >();
var closedSet = new HashSet <TState>();
var cameFrom = new Dictionary <TState, (TState parent, IProblemAction move)>();
var initialState = problem.GetInitialState();
openSet.PushOrImprove(0, new StateCost <TState>(initialState, 0));
cameFrom.Add(initialState, (default(TState), null));
while (!openSet.IsEmpty)
{
var stateCost = openSet.PopMin();
var state = stateCost.State;
var cost = stateCost.Cost;
closedSet.Add(state);
StatesEvaluated++;
MaxCostEvaulated = Math.Max(MaxCostEvaulated, cost);
if (problem.IsGoal(state))
{
return(RebuildSolution(cameFrom, state));
}
foreach (var move in problem.Expand(state))
{
var(successor, stepCost) = problem.ApplyAction(state, move);
if (closedSet.Contains(successor))
{
continue;
}
// why is this 1 and not step cost? because that's how we enforce
// the BFS property of exploring on level fully before starting the next
var wasImprovement = openSet.PushOrImprove(cost + 1, new StateCost <TState>(successor, cost + 1));
if (wasImprovement)
{
cameFrom[successor] = (state, move);
}
}
}
return(null);
}
private double Search(TState state, TState parent, double pathCost, Stack <IProblemAction> path, double bound)
{
var f = pathCost + heuristic(state);
StatesEvaluated++;
if (f > bound)
{
return(f);
}
if (problem.IsGoal(state))
{
return(FOUND);
}
var min = double.MaxValue;
var actions = problem.Expand(state);
foreach (var action in actions)
{
var(successor, stepCost) = problem.ApplyAction(state, action);
var successorPathCost = pathCost + stepCost;
// TODO: so many assumptions here
if (successor.Equals(parent))
{
continue;
}
path.Push(action);
var result = Search(successor, state, successorPathCost, path, bound);
if (result == FOUND)
{
return(FOUND);
}
min = Math.Min(min, result);
path.Pop();
}
return(min);
}
