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);
}
