import java.io.*; import java.awt.*; import java.util.*; //--------------------------------------------------------------------- //--------------------------------------------------------------------- // // The River World // //--------------------------------------------------------------------- //--------------------------------------------------------------------- class River implements State, Cloneable { private boolean same_side(Creature one, Creature two) { return one.which_side() == two.which_side(); } public State get_initial() { River tempState = new River(false,false,false,false); return tempState; } public State get_goal() { River tempState = new River(true,true,true,true); return tempState; } public State get_copy() throws Exception { River temp = (River) this.clone(); temp.theFarmer = this.theFarmer.get_copy(); temp.theWolf = this.theWolf.get_copy(); temp.theGoat = this.theGoat.get_copy(); temp.theCabbage = this.theCabbage.get_copy(); return temp; } public boolean equals(State s) { River r = (River) s; return (theWolf.which_side() == r.theWolf.which_side()) && (theGoat.which_side() == r.theGoat.which_side()) && (theCabbage.which_side() == r.theCabbage.which_side()) ; } public void apply(Object operator) throws Exception { theFarmer.change_side(); // the farmer always moves! if( ((String) operator).compareTo("move_wolf") == 0) theWolf.change_side(); else if( ((String) operator).compareTo("move_goat") == 0) theGoat.change_side(); else if( ((String) operator).compareTo("move_cabbage") == 0) theCabbage.change_side(); } public boolean legal_state() { if ( same_side(theFarmer,theGoat) ) return true; // if Farmer with goat, nothing can happen. else if ( same_side(theWolf, theGoat )) return false; // Wolf and Goat left alone -> bloody mess else if (same_side(theGoat,theCabbage )) return false; // Goat and cabbage left along -> bad else return true; } public Stack possible_operators() { Stack moves = new Stack(); moves.push("move_farmer"); if(same_side(theFarmer,theWolf)) moves.push("move_wolf"); if(same_side(theFarmer,theGoat)) moves.push("move_goat"); if(same_side(theFarmer,theCabbage)) moves.push("move_cabbage"); return moves; } public Creature theFarmer; public Creature theWolf; public Creature theGoat; public Creature theCabbage; public static void main (String [] args) throws Exception { } public River() // Constructor { theFarmer = new Creature("F"); theWolf = new Creature("W"); theGoat = new Creature("G"); theCabbage = new Creature("C"); } public River(boolean f_side, boolean w_side, boolean g_side, boolean c_side) // Constructor { theFarmer = new Creature("F"); theWolf = new Creature("W"); theGoat = new Creature("G"); theCabbage = new Creature("C"); theFarmer.set_side(f_side); theWolf.set_side(w_side); theGoat.set_side(g_side); theCabbage.set_side(c_side); } public void paint(Graphics window) { window.setColor(Color.cyan); window.fillRect(180,0,200,600); // Paint river. theFarmer.paint(window); theWolf.paint(window); theGoat.paint(window); theCabbage.paint(window); } } // end of River class class Creature implements Cloneable { private int center_x=150; int center_y; private int width = 30; int height = 20; private boolean side; private String species; public Creature(String input_species) { species = input_species; if(species.compareTo("W")==0) center_y=250; else if (species.compareTo("G")==0) center_y = 280; else if (species.compareTo("C")==0) center_y = 310; else center_y = 220; } public Creature get_copy() throws Exception {return (Creature) this.clone();} public void setCenterCoordinates(int new_x, int new_y) { center_x = new_x; center_y = new_y; } public boolean which_side() {return side;} public void change_side() {side = !side;} public void set_side(boolean input_side) {side = input_side;} public void paint(Graphics window) { int x = center_x; if(side) x+= 255; if(species.compareTo("W")==0) window.setColor(Color.black); else if (species.compareTo("G")==0) window.setColor(Color.red); else if (species.compareTo("C")==0) window.setColor(Color.green); else window.setColor(Color.blue); window.drawString(species,x-5,center_y+5); window.drawOval(x-(width/2),center_y - (height/2),width,height); } } // end of Creature class //------------------------------------------------------------------------- //------------------------------------------------------------------------- // // PLANNER (the state space search engine) is below. // //------------------------------------------------------------------------- //------------------------------------------------------------------------- interface State { // Essential methods: public State get_initial(); public State get_goal(); public State get_copy() throws Exception; public boolean equals(State s); public void apply(Object operator) throws Exception; public boolean legal_state(); public Stack possible_operators(); public void paint(Graphics g); // Nice-to-have's: // public boolean valid_goal(State init, State goal); // public void graph_plan(Plan solution); } class Plan extends Queue implements Cloneable { public Object popPlan() { return popQ(); } public void pushPlan(Object operator) { pushQ(operator); } public Plan get_copy() { return (Plan) this.clone(); } public void Print() { Plan local_plan = get_copy(); System.out.println("\n A plan: "); while(!local_plan.empty()) { String s = (String) local_plan.pop(); System.out.println(" " + s); } System.out.println("\n"); } } class Planner extends Frame { public Graphics g; public static Color background_color; State initial; State goal; State current_state; Queue plan_queue = new Queue(); public static void main (String [] args) throws Exception { River bloodRiver = new River(); Planner DeepThought = new Planner(bloodRiver); Plan p = DeepThought.solve(); p.Print(); DeepThought.animatePlan(p); } public Planner(State s) throws Exception // Constructor { super(" Blood River "); setSize(600,600); setBackground(Color.white); background_color = getBackground(); setVisible(true); g = getGraphics(); initial = s.get_initial(); goal = s.get_goal(); current_state = initial.get_copy(); // Initialize current state to copy of init. } public State apply_plan(Plan p, State s) throws Exception { Plan localp = p.get_copy(); State temp_state = s.get_copy(); int count = 1; while(!localp.empty()) { System.out.println("\n Number of ops in plan: "+count); count++; temp_state.apply(localp.popPlan()); } return temp_state; } public Plan solve() throws Exception { Plan p = new Plan(); State s; Stack operators = new Stack(); plan_queue.pushQ( p ); boolean solved = false; while( !solved && !plan_queue.empty() ) { p = (Plan) plan_queue.popQ(); p.Print(); s = apply_plan(p,initial); State temp_state; if( goal.equals(s) ) {solved = true; System.out.println("\n Solved!\n"); temp_state = s; paint(g); Thread.sleep(2000);} else { if (s.legal_state()) { operators = s.possible_operators(); System.out.println("\n About to add children plans! "); int i = 0; while(!operators.empty()) { Plan child_plan = p.get_copy(); child_plan.pushPlan( operators.pop() ); child_plan.Print(); plan_queue.pushQ(child_plan); System.out.println(" " + i + " "); i++; } } } } if(solved) { return p; } else return new Plan(); } public void animatePlan(Plan p) throws Exception { current_state = initial.get_copy(); paint(g); Thread.sleep(2000); while(!p.empty()) { current_state.apply(p.popPlan()); paint(g); System.out.println("\n Here I am at "); Thread.sleep(2000); } } public void paint(Graphics window) { window.clearRect(0,0,600,600); current_state.paint(window); } }