Puzzle PuzzleGenerator::SimulatedAnnealing_Linear(Puzzle p, double temp_start, double delta, double epsilon)
{
// Function that uses simulated annealing algorithm to find best value puzzle.
// TEMP_START = initial temperature
// DELTA = amount that temperature decreases per iteration
// returns the best puzzle found
Puzzle current = p;
// Keep track of the time so we don't exceed it.
Timer t;
t.StartTimer();
int i = 0; // iteration counter (for debugging)
double temperature = temp_start;
while (temperature > epsilon)
{
//printf ("\nSIMULATED ANNEALING ITERATION %i\n", i);
// get random successor
Puzzle successor = current.GetRandomSuccessor();
//printf ("current value = %i\n", current.GetValue());
//printf ("successor value = %i\n", successor.GetValue());
//printf ("temperature = %f\n", temperature);
// if successor is a "good" move accept it
if (successor.GetValue() > current.GetValue())
{
//printf("successor value > current value...ACCEPTED!\n");
current = successor;
}
else // otherwise accept the move with probability of e^(deltaE/temperature)
{
int deltaE = successor.GetValue() - current.GetValue(); // calculate delta E
//printf("deltaE = %i\n", deltaE);
double randVal = (rand() % 1000) / 1000.0; // generate random value between (0,1)
//printf("randVal = %f\n", randVal);
double thresh = exp(deltaE/temperature);
//printf("thresh = %f\n", thresh);
if (randVal < thresh)
{
//printf("successor value randomly ACCEPTED\n");
current = successor;
}
}
// cool temperature each iteration
temperature -= delta;
// increment iteration counter
i++;
}
return current;
}
/**
* Function that uses simulated annealing algorithm to find best value puzzle.
* TEMP_START = initial temperature
* ALPHA = how much the temperature is 'cooled' each iteration
* EPSILON = when temperature reaches the epsilon we're done
* returns the best puzzle found
**/
Puzzle PuzzleGenerator::SimulatedAnnealing_Exp(Puzzle p, double temp_start, double alpha, double epsilon)
{
Puzzle current = p;
// Keep track of the time so we don't exceed it.
Timer t;
t.StartTimer();
int i = 0; // iteration counter (for debugging)
double temperature = temp_start;
while (temperature > epsilon)
{
// get random successor
Puzzle successor = current.GetRandomSuccessor();
// if successor is a "good" move accept it
if (successor.GetValue() > current.GetValue())
{
current = successor;
}
else // otherwise accept the move with probability of e^(deltaE/temperature)
{
int deltaE = successor.GetValue() - current.GetValue(); // calculate delta E
double randVal = (rand() % 1000) / 1000.0; // generate random value between (0,1)
double thresh = exp(deltaE/temperature);
if (randVal < thresh)
{
//printf("successor value randomly ACCEPTED\n");
current = successor;
}
}
// cool temperature each iteration
temperature *= alpha;
// increment iteration counter
i++;
}
return current;
}
Puzzle PuzzleGenerator::GeneratePuzzle()
{
timer.StartTimer();
maxtime = 58.0; // to make sure we don't exceed a minute
// Declare variables for Simulated Annealing Algorithm
double startingTemp;
double alpha;
double epsilon;
// Determine if puzzle is "large" or not (so we can adjust how the algorithm performs)
if (nRows*nColumns >= 80 || nRows*nColumns*(maxVal - minVal - 1) > 500)
{
startingTemp = 100;
alpha = 0.9999;
epsilon = 0.001;
}
else
{
startingTemp = 100;
alpha = 0.999;
epsilon = 0.001;
}
Puzzle startingPuzzle(nRows, nColumns, minVal, maxVal);
Puzzle bestPuzzle = SimulatedAnnealing_Exp(startingPuzzle, startingTemp, alpha, epsilon);
int i = 0;
while (timer.GetElapsedTime() < maxtime)
{
startingPuzzle = Puzzle(nRows, nColumns, minVal, maxVal);
Puzzle p = SimulatedAnnealing_Exp(startingPuzzle, startingTemp, alpha, epsilon);
if (p.GetValue() > bestPuzzle.GetValue())
{
bestPuzzle = p;
}
i++;
}
return bestPuzzle;
}
/** NOT USED (Simulated Annealing is Superior) **/
Puzzle PuzzleGenerator::HillClimbing(double timelimit, Puzzle p)
{
// Function that uses hillclimbing algorithm to find best value puzzle.
// Returns best puzzle found after timelimit or local max when if it is found before time limit
Puzzle bestPuzzle = p;
// Keep track of the time so we don't exceed it.
Timer t;
t.StartTimer();
while (t.GetElapsedTime() < timelimit-0.1)
{
// Generate all successors of bestPuzzle
vector<Puzzle> successors;
bestPuzzle.GetAllSuccessors(successors);
Puzzle bestSuccessor = successors[0];
// Determine highest valued successor and save as new best puzzle
for (vector<Puzzle>::size_type i = 0; i != successors.size(); i++)
{
if (successors[i].GetValue() > bestSuccessor.GetValue())
{
bestSuccessor = successors[i];
}
}
// Make sure that best successor is better than its parent (bestPuzzle), save it as the new best puzzle, and loop.
if (bestSuccessor.GetValue() > bestPuzzle.GetValue())
{
bestPuzzle = bestSuccessor;
}
else
{
// If it's not better, we found a local maximum. Save it and
return bestPuzzle;
}
}
printf("time limit reached\n");
return bestPuzzle;
}