// This function does the actual solving.
void solvePuzzle(PuzzleState *start, BagOfPuzzleStates &active, PredDict &seen, vector<PuzzleState*> &solution) {
PuzzleState *state;
PuzzleState *temp;
active.put_in(start); // Must explore the successors of the start state.
seen.add(start,NULL); // We've seen this state. It has no predecessor.
int foo=0;
while (!active.is_empty()) {
// Loop Invariants:
// 'seen' contains the set of puzzle states that we know how to reach.
// 'active' contains the set of puzzle states that we know how to reach,
// and whose successors we might not have explored yet.
foo++;
if (foo % 1000 == 0) cout << foo << endl;
state = active.take_out();
// Note: Do not delete this, as this PuzzleState is also in 'seen'
// The following two lines are handy for debugging, or seeing what
// the algorithm is doing.
// 221 STUDENTS: Comment these out when you want the program to
// run at full speed!
//cout << "Exploring State: \n";
//state->print(cout);
//usleep(100000); // Pause for some microseconds, to let human read output
if (state->isSolution()) {
// Found a solution!
cout << "Found solution! \n";
state->print(cout);
// Follow predecessors to construct path to solution.
temp = state;
while (temp!=NULL) {
solution.push_back(temp);
// Guaranteed to succeed, because these states must have been
// added to dictionary already.
seen.find(temp,temp);
}
return;
}
vector<PuzzleState*> nextMoves = state->getSuccessors();
for (unsigned int i=0; i < nextMoves.size(); i++) {
if (!seen.find(nextMoves[i], temp)) {
// Never seen this state before. Add it to 'seen' and 'active'
active.put_in(nextMoves[i]);
seen.add(nextMoves[i], state);
} else {
delete nextMoves[i];
}
}
}
// Ran out of states to explore. No solution!
solution.clear();
return;
}
// This function does the actual solving.
void solvePuzzle(PuzzleState *start, TodoList<PuzzleState*> &active, PredDict<PuzzleState*> &seen, vector<PuzzleState*> &solution) {
PuzzleState *state;
PuzzleState *temp;
active.add(start); // Must explore the successors of the start state.
seen.add(start,NULL); // We've seen this state. It has no predecessor.
while (!active.is_empty()) {
// Loop Invariants:
// 'seen' contains the set of puzzle states that we know how to reach.
// 'active' contains the set of puzzle states that we know how to reach,
// and whose successors we might not have explored yet.
state = active.remove();
// Note: Do not delete this, as this PuzzleState is also in 'seen'
// uncomment the next two lines for debugging, if you'd like!
// cout << "Exploring State: \n";
// state->print(cout);
// cin.get();
if (state->isSolution()) {
// Found a solution!
cout << "Found solution! \n";
state->print(cout);
// Follow predecessors to construct path to solution.
temp = state;
while (temp!=NULL) {
solution.push_back(temp);
// Guaranteed to succeed, because these states must have been
// added to dictionary already.
seen.find(temp,temp);
}
return;
}
vector<PuzzleState*> nextMoves = state->getSuccessors();
for (unsigned int i=0; i < nextMoves.size(); i++) {
if (!seen.find(nextMoves[i], temp)) {
// Never seen this state before. Add it to 'seen' and 'active'
active.add(nextMoves[i]);
seen.add(nextMoves[i], state);
}
else {
// We're not using this duplicate state;
// so, we should delete it.
delete nextMoves[i];
}
}
}
// Ran out of states to explore. No solution!
cout << "No solution!" << endl;
solution.clear();
return;
}
int operator() (PuzzleState &left, PuzzleState &right) {
// This is an inefficient implementation, but it has
// the desired functionality, doesn't require breaking the API
// of the PuzzleState class, and is easy to code.
ostringstream left_stream;
ostringstream right_stream;
left.print(left_stream);
right.print(right_stream);
return left_stream.str().compare(right_stream.str());
}
int main( int argc, char *argv[] )
{
cout << "STL A* 8-puzzle solver implementation\n(C)2001 Justin Heyes-Jones\n";
bool bUserBoard = false;
if( argc > 1 )
{
char *userboard = argv[1];
int i = 0;
int c;
while( c = argv[1][i] )
{
if( isdigit( c ) )
{
int num = (c - '0');
PuzzleState::g_start[i] = static_cast<PuzzleState::TILE>(num);
}
i++;
}
}
// Create an instance of the search class...
AStarSearch<PuzzleState> astarsearch;
int NumTimesToSearch = NUM_TIMES_TO_RUN_SEARCH;
while( NumTimesToSearch-- )
{
// Create a start state
PuzzleState nodeStart( PuzzleState::g_start );
// Define the goal state
PuzzleState nodeEnd( PuzzleState::g_goal );
// Set Start and goal states
astarsearch.SetStartAndGoalStates( nodeStart, nodeEnd );
unsigned int SearchState;
unsigned int SearchSteps = 0;
do
{
SearchState = astarsearch.SearchStep();
#if DEBUG_LISTS
float f,g,h;
cout << "Search step " << SearchSteps << endl;
cout << "Open:\n";
PuzzleState *p = astarsearch.GetOpenListStart( f,g,h );
while( p )
{
((PuzzleState *)p)->PrintNodeInfo();
cout << "f: " << f << " g: " << g << " h: " << h << "\n\n";
p = astarsearch.GetOpenListNext( f,g,h );
}
cout << "Closed:\n";
p = astarsearch.GetClosedListStart( f,g,h );
while( p )
{
p->PrintNodeInfo();
cout << "f: " << f << " g: " << g << " h: " << h << "\n\n";
p = astarsearch.GetClosedListNext( f,g,h );
}
#endif
// Test cancel search
#if 0
int StepCount = astarsearch.GetStepCount();
if( StepCount == 10 )
{
astarsearch.CancelSearch();
}
#endif
SearchSteps++;
}
while( SearchState == AStarSearch<PuzzleState>::SEARCH_STATE_SEARCHING );
if( SearchState == AStarSearch<PuzzleState>::SEARCH_STATE_SUCCEEDED )
{
#if DISPLAY_SOLUTION_FORWARDS
cout << "Search found goal state\n";
#endif
PuzzleState *node = astarsearch.GetSolutionStart();
#if DISPLAY_SOLUTION_FORWARDS
cout << "Displaying solution\n";
#endif
int steps = 0;
#if DISPLAY_SOLUTION_FORWARDS
node->PrintNodeInfo();
cout << endl;
#endif
for( ;; )
{
node = astarsearch.GetSolutionNext();
if( !node )
{
break;
}
#if DISPLAY_SOLUTION_FORWARDS
node->PrintNodeInfo();
cout << endl;
#endif
steps ++;
};
#if DISPLAY_SOLUTION_FORWARDS
// todo move step count into main algorithm
cout << "Solution steps " << steps << endl;
#endif
////////////
node = astarsearch.GetSolutionEnd();
#if DISPLAY_SOLUTION_BACKWARDS
cout << "Displaying reverse solution\n";
#endif
steps = 0;
node->PrintNodeInfo();
cout << endl;
for( ;; )
{
node = astarsearch.GetSolutionPrev();
if( !node )
{
break;
}
#if DISPLAY_SOLUTION_BACKWARDS
node->PrintNodeInfo();
cout << endl;
#endif
steps ++;
};
#if DISPLAY_SOLUTION_BACKWARDS
cout << "Solution steps " << steps << endl;
#endif
//////////////
// Once you're done with the solution you can free the nodes up
astarsearch.FreeSolutionNodes();
}
else if( SearchState == AStarSearch<PuzzleState>::SEARCH_STATE_FAILED )
{
#if DISPLAY_SOLUTION_INFO
cout << "Search terminated. Did not find goal state\n";
#endif
}
else if( SearchState == AStarSearch<PuzzleState>::SEARCH_STATE_OUT_OF_MEMORY )
{
#if DISPLAY_SOLUTION_INFO
cout << "Search terminated. Out of memory\n";
#endif
}
// Display the number of loops the search went through
#if DISPLAY_SOLUTION_INFO
cout << "SearchSteps : " << astarsearch.GetStepCount() << endl;
#endif
}
return 0;
}