/** 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;
}
/** NOT USED (Example Code provided by professor) **/
Puzzle PuzzleGenerator::RandomWalk(double timelimit)
{
// A very simple function that start at a random configuration and keeps randomly modifying it
// until it hits the time limit. Returns the best solution found so far.
Puzzle p(nRows, nColumns, minVal, maxVal); // Generate a random puzzle with the specified values.
// Keep track of the best puzzle found so far (and its value).
Puzzle bestPuzzle = p;
int bestValue = p.GetValue();
// Keep track of the time so we don't exceed it.
Timer t;
t.StartTimer();
// Loop until we hit the time limit.
while (t.GetElapsedTime() < timelimit-0.1) // To make sure that we don't exceed the time limit, we stop just before we hit the time limit.
{
// Generate a successor of p by randomly changing the value of a random cell
// (since we are doing a random walk, we just replace p with its successor).
p = p.GetRandomSuccessor();
// Update the current best solution.
if (p.GetValue() > bestValue) // Calling GetValue() for the first time is costly
// since the puzzle has to be evaluated first.
{
bestValue = p.GetValue(); // Calling it a second time simply returns the value that was computed before.
bestPuzzle = p;
}
}
return bestPuzzle;
// The following code is not executed in this function. It exists just as an example for getting all the successors of a puzzle.
vector<Puzzle> successors;
bestPuzzle.GetAllSuccessors(successors);
}
