@@ -342,9 +342,9 @@
 			                       "DU","DD","DL","DR",
 			                       "LU","LD","LL","LR",
 			                       "RU","RD","RL","RR","UUU","UUUU","UUUUU"];
 			PredictFuture = 20;
-			clear_improvement = 3;
+			clear_improvement = 1;
 		}
 		else if(g.map.W*g.map.H <= 4096) {
 			RandomChoicePattern = ["UUU","U","D","L","R","UD","DU","LR","RL"];
 			PredictFuture = 10;
@@ -374,9 +374,8 @@
 
 		// Follow the predicted plan.
 		if( plan.empty )
 			return 'A';
-stderr.writeln(plan, " ", plan_state);
 		char c = plan[0];
 		plan = plan[1..$];
 		int b_lambda = current_game.map.collected_lambda;
 		current_game.command(c);
@@ -428,14 +427,12 @@
 	}
 
 	void replan()
 	{
-stderr.writeln("replan!");
 		// Try to replace every step of the plan by another move.
 		Game g = current_game.clone();
 		Tuple!(SubSolver, string, int) cand = tuple(sub_solver, plan, Tentative_Stuck);
 		int insertion_point = plan.length;
-writeln(cand, " ", cand[0].g.map.collected_lambda);
 		bool tiebreak_by_turn = false;
 		int consider_length = min(ReplanLength, g.map.W*g.map.H);
 		if(cand[0].g.cleared) consider_length = min(consider_length, cand[1].length);
 
@@ -466,9 +463,8 @@
 						cand = r;
 						tiebreak_by_turn = true;
 						insertion_point = i+prefix.length;
 						if(r[0].g.cleared) consider_length = min(consider_length, r[1].length);
-writeln(cand, " ", cand[0].g.map.collected_lambda);
 					}
 				}
 			g.command(plan[i]);
 		}
@@ -510,7 +506,173 @@
 		return tuple(s, log, state);
 	}
 }
 
-alias Solver_2!(Solver_1) MainSolver;
+class Queue(T)
+{
+	alias Tuple!(T,int) t;
+
+	t[] cur, next;
+
+	void push(T v, int p) { (cur.empty ? cur : next) ~= tuple(v,p); }
+	bool empty() { return cur.empty; }
+	t pop() {
+		t v = cur[0]; cur = cur[1..$];
+		if(cur.empty) { cur = next; next = null; }
+		return v;
+	}
+}
+
+class Solver_3 : Solver
+{
+	Game g;
+	this(in Game g)
+	{
+		this.g = g.clone();
+	}
+
+	char single_step()
+	{
+		char c = think(g);
+		if(c != 'A')
+			g.command(c);
+		return c;
+	}
+
+	void force(char c)
+	{
+stderr.writeln(death_move(g));
+		if(c != 'A')
+			g.command(c);
+	}
+
+	bool is_spacy(char c) {
+		return c==' ' || c=='.' || c=='R' || c=='!' || c=='\\' || c=='O';
+	}
+	bool is_rocky(char c) {
+		return c=='*' || c=='@';
+	}
+	bool is_true_space(char c) {
+		return c==' ';
+	}
+	bool is_trampoline_source(char c) {
+		return 'A'<=c && c<='I';
+	}
+	bool is_rocklambda(char c) {
+		return is_rocky(c) || c=='\\';
+	}
+
+	string death_move(in Game g)
+	{
+		// TODO: S
+		string death;
+		int y = g.map.robot.y;
+		int x = g.map.robot.x;
+		int[5] dy_=[-1,+1,0,0,0];
+		int[5] dx_=[0,0,-1,+1,0];
+		char[] ds=['D','U','L','R','W'];
+		for(int i=0; i<5; ++i)
+		{
+			bool after_move_death(int y, int x, char tr_tgt)
+			{
+				bool is_spacy_t(char c) {
+					if(is_spacy(c) || c==tr_tgt)
+						return true;
+					return ('A'<=c && c<='I' && g.tr.target_of(c)==tr_tgt);
+				}
+
+				// check water
+				if( g.hp==0 && y<=g.water_level )
+					return true;
+
+				// check falling rock.
+				int yy=y+1, xx=x;
+				if( is_spacy_t(g.map[yy, xx]) )
+				{
+					if( is_rocky(g.map[yy+1,xx]) )
+						return true;
+					if( is_spacy_t(g.map[yy+1,xx]) && is_rocky(g.map[yy+1,xx+1]) && is_rocky(g.map[yy,xx+1]) ) {
+						if( is_spacy_t(g.map[yy+1,xx+2]) && is_spacy_t(g.map[yy,xx+2]) )
+							return false;
+						return true;
+					}
+					if( is_spacy_t(g.map[yy+1,xx]) && is_rocky(g.map[yy+1,xx-1]) && is_rocklambda(g.map[yy,xx-1]) ) {
+						if(g.hige_until_rise == 1 && g.map[yy+1,xx+1]=='W')
+							return false;
+						return true;
+					}
+				}
+				return false;
+			}
+
+			int dy=dy_[i], dx=dx_[i];
+			if( is_spacy(g.map[y+dy,x+dx])
+			 || dy==0 && is_rocky(g.map[y,x+dx]) && is_true_space(g.map[y,x+2*dx]) )
+			{
+				if( after_move_death(y+dy, x+dx, char.init) )
+					death ~= ds[i];
+			}
+			else if( is_trampoline_source(g.map[y+dy,x+dx]) )
+			{
+				Pos p = g.tr.target_pos(g.map[y+dy,x+dx]);
+				if( after_move_death(p.y, p.x, g.tr.target_of(g.map[y+dy,x+dx])) )
+					death ~= ds[i];
+			}
+			else
+			{
+				death ~= ds[i];
+			}
+		}
+		return death;
+	}
+
+	char think(in Game g)
+	{
+		string s = death_move(g);
+		stderr.writeln(s);
+
+		auto Q = new Queue!(Tuple!(Pos,Pos));
+		Q.push(tuple(g.map.robot.clone(), g.map.robot.clone()), 0);
+		Pos[][] V = new Pos[][](g.map.H+2, g.map.W+2);
+		while(!Q.empty) {
+			auto tup = Q.pop();
+			Pos  p    = tup[0][0];
+			Pos  prev = tup[0][1];
+			int  dist = tup[1];
+			if(V[p.y][p.x])
+				continue;
+			V[p.y][p.x] = prev;
+			if(g.map[p]=='\\' || g.map[p]=='O')
+			{
+				Pos goback(Pos p) {
+					return V[p.y][p.x];
+				}
+				for(;;) {
+					Pos q = goback(p);
+					if(q == g.map.robot)
+						if(q.y==p.y)
+							return q.x<p.x ? 'R' : 'L';
+						else
+							return q.y<p.y ? 'U' : 'D';
+					p=q;
+				}
+			}
+
+			int[4] dy=[-1,+1,0,0];
+			int[4] dx=[0,0,-1,+1];
+			char[] ds=['D','U','L','R'];
+			for(int i=0; i<4; ++i)
+			{
+				int y=p.y+dy[i], x=p.x+dx[i];
+				if((g.map[y,x]==' '||g.map[y,x]=='\\'||g.map[y,x]=='.'||g.map[y,x]=='O')&&!V[y][x]) {
+					Q.push(tuple(new Pos(y,x),p), dist+1);
+				}
+			}
+		}
+		return 'A';
+	}
+}
+
+alias Solver_3 MainSolver;
+//alias Solver_2!(Solver_1) MainSolver;
 //alias Solver_1 MainSolver;
 //alias Solver_0 MainSolver;