POJ3414 —— Bfs基础模板代码

Program poj3414;//By_Thispoet
Const 
	maxn=100;
Var
	v			:Array[0..maxn,0..maxn]of Boolean;
	h,t,p,q		:Longint;
	a,b,c,i,j	:Longint;
	seq			:Array[1..maxn*maxn*10]of record l,r,fa,did:Longint;end;
	ans			:Array[0..maxn*maxn]of Longint;
	flag		:Boolean;
	
Function Check(i:Longint):Boolean;
begin
	if (seq[i].l=c)or(seq[i].r=c) then 
		begin
			flag:=true;
			exit(true);
		end;
	exit(false);
end;
	
	
Function Min(i,j:Longint):Longint;
begin
	if i<j then exit(i);exit(j);
end;
	
	
Procedure Printf();
begin
	writeln(ans[0]);
	while ans[0]>0 do 
		begin
			case ans[ans[0]] of 
				1:writeln('FILL(1)');
				2:writeln('FILL(2)');
				3:writeln('DROP(1)');
				4:writeln('DROP(2)');
				5:writeln('POUR(2,1)');
				6:writeln('POUR(1,2)');
			end;
			dec(ans[0]);
		end;
end;
	
	
BEGIN

	readln(a,b,c);
	fillchar(v,sizeof(v),0);
	h:=0;t:=1;seq[1].l:=0;seq[1].r:=0;
	seq[1].fa:=0;flag:=false;
	while h<t do 
		begin
			inc(h);
			i:=seq[h].l;j:=seq[h].r;
			if not v[a,j] then 
				begin
					v[a,j]:=true;
					inc(t);
					seq[t].l:=a;seq[t].r:=j;
					seq[t].fa:=h;seq[t].did:=1;
				end;
			if check(t) then break;
			if not v[i,b] then 
				begin
					v[i,b]:=true;
					inc(t);
					seq[t].l:=i;seq[t].r:=b;
					seq[t].fa:=h;seq[t].did:=2;
				end;
			if check(t) then break;
			if not v[0,j] then 
				begin
					v[0,j]:=true;
					inc(t);
					seq[t].l:=0;seq[t].r:=j;
					seq[t].fa:=h;seq[t].did:=3;
				end;
			if check(t) then break;
			if not v[i,0] then 
				begin
					v[i,0]:=true;
					inc(t);
					seq[t].l:=i;seq[t].r:=0;
					seq[t].fa:=h;seq[t].did:=4;
				end;
			if check(t) then break;
			p:=Min(a,i+j);q:=i+j-p;
			if not v[p,q] then
				begin
					v[p,q]:=true;
					inc(t);
					seq[t].l:=p;seq[t].r:=q;
					seq[t].fa:=h;seq[t].did:=5;
				end;
			if check(t) then break;
			q:=Min(b,i+j);p:=i+j-q;
			if not v[p,q] then 
				begin
					v[p,q]:=true;
					inc(t);
					seq[t].l:=p;seq[t].r:=q;
					seq[t].fa:=h;seq[t].did:=6;
				end;
		end;
	if not flag then writeln('impossible')else
		begin
			fillchar(ans,sizeof(ans),0);
			while t>1 do 
				begin
					inc(ans[0]);
					ans[ans[0]]:=seq[t].did;
					t:=seq[t].fa;
				end;
			printf();
		end;

END.