Modify move-hint code to make use of the fact that solving lights out involves pressing each button N (mod states) times.

Fixes #8

Author: jigpu

source/Light.cpp

@@ -47,6 +47,7 @@ Light::Light(unsigned int states) {
 
 	this->states = states;
 	state = 0;
+	presses = 0;
 
 	paintMutex = SDL_CreateMutex();
 
@@ -132,3 +133,19 @@ bool Light::paint(SDL_Surface& surface, unsigned int width, unsigned int height)
 	}
 }
 
+
+void Light::press() {
+	SDL_mutexP(paintMutex);
+	presses++;
+	if (presses >= states)
+		presses = 0;
+	
+	dirty = true;
+	SDL_mutexV(paintMutex);
+}
+
+
+bool Light::shouldPress() const {
+	return presses != 0;
+}
+

source/Light.hpp

@@ -63,6 +63,13 @@ class Light : public Renderable {
 	 */
 	unsigned int state, states;
 
+	/**
+	 * The number of presses the light has recieved. A game of
+	 * LightsOut can be solved by pressing each light N (mod
+	 * states) times.
+	 */
+	unsigned int presses;
+	
 	/**
 	 * A mutex to prevent the change of internal object state
 	 * while a paint is taking place (or vice-versa).
@@ -79,19 +86,37 @@ class Light : public Renderable {
 	~Light();
 
 	/**
-	 * Returns true if the light is on.
+	 * Returns true if the light is on. This method is influenced
+	 * by calls to the "nextState" method.
 	 */
 	bool isLightOn() const;
 
 	/**
 	 * Cycles the light to the next available state. Lights at
 	 * the highest available state will be reset to the "off"
-	 * state.
+	 * state. The "press" method should be called in addition to
+	 * this if the light was the direct recipient of a press.
 	 */
 	void nextState();
 
 	bool paint(SDL_Surface& surface, unsigned int width, unsigned int height) const;
 
+	/**
+	 * Lets the light know that it was the direct recipeient of a
+	 * press. This is used to keep track of lights need to be
+	 * pressed to reset the game to an all-off state. The
+	 * "nextState" method should be called as well to ensure that
+	 * the light actually changes color from the press.
+	 */
+	void press();
+	
+	/**
+	 * Returns true if the light should be pressed to arrive at
+	 * an all-off state. This method is influenced by calls to
+	 * the "press" method.
+	 */
+	bool shouldPress() const;
+	
 };
 
 

source/LightsOutGame.cpp

@@ -167,45 +167,42 @@ void LightsOutGame::eventOccured(const SDL_Event* const event) {
 
 
 void LightsOutGame::getMoveHint(unsigned int& suggestedX, unsigned int& suggestedY) const {
+	bool won = winningState();
+	if (won) {
+		std::clog << SDL_GetTicks() << " (" << this << "): Game has already been won, providing bogus hint of (0,0)." << std::endl;
+		suggestedX = 0;
+		suggestedY = 0;
+		return;
+	}
+	
 	SDL_mutexP(paintMutex);
-	for (unsigned int y=0; y<lights->getHeight(); y++) {
-		for (unsigned int x=0; x<lights->getWidth(); x++) {
-			if (lights->getTile(x,y)->object->isLightOn()) {
-				if (y+1 != lights->getHeight()) {
-					//"Chase the lights"
-					suggestedX = x;
-					suggestedY = y+1;
-					SDL_mutexV(paintMutex);
-					return;
-				}
-				else {
-					//Fixing the top
-					suggestedY = 0;
-					switch (x) {
-						case 0: suggestedX = 1; SDL_mutexV(paintMutex); return;
-						case 1: suggestedX = 0; SDL_mutexV(paintMutex); return;
-						case 2: suggestedX = 3; SDL_mutexV(paintMutex); return;
-					}
-				}
-			}
+	bool moveAvailable = false;
+	for (unsigned int x=0; x<lights->getWidth(); x++) {
+		for (unsigned int y=0; y<lights->getHeight(); y++) {
+			moveAvailable = moveAvailable || lights->getTile(x,y)->object->shouldPress();
 		}
 	}
-	
-	//There's no reasonable "hint" for a board that has already won ;)
-	if (winningState()) {
-		std::clog << SDL_GetTicks() << " (" << this << "): Game has already been won, providing bogus hint of (0,0)." << std::endl;
+	SDL_mutexV(paintMutex);
+	if (!moveAvailable) {
+		std::clog << SDL_GetTicks() << " (" << this << "): Game not won, yet no move available?? Providing bogus hint of (0,0)." << std::endl;
 		suggestedX = 0;
 		suggestedY = 0;
-		SDL_mutexV(paintMutex);
 		return;
 	}
 
-	//Unsolvable
-	//How on earth we got here after the constructor ensured
-	//the board was solvable is beyond me.
-	std::cerr << "Game is not solvable, cannot give move hint." << std::endl;
+	SDL_mutexP(paintMutex);
+	int x=0;
+	int y=0;
+	do {
+		x = rand()%lights->getWidth();
+		y = rand()%lights->getHeight();
+	} while (!(lights->getTile(x,y)->object->shouldPress()));
 	SDL_mutexV(paintMutex);
-	throw 10;
+	
+	suggestedX = x;
+	suggestedY = y;
+	
+	return;
 }
 
 
@@ -402,6 +399,7 @@ void LightsOutGame::pressButton(unsigned int x, unsigned int y) {
 
 	moves++;
 
+	lights->getTile(x,y)->object->press();
 	toggleLight(x,y);
 	toggleLight(x-1,y);
 	toggleLight(x+1,y);