记录编号	661	评测结果	AATWA
题目名称	[NOIP 2002]字串变换	最终得分	30
用户昵称	chengyang	是否通过	未通过
代码语言	Pascal	运行时间	1.032 s
提交时间	2008-07-20 14:37:47	内存使用	0.00 MiB

program stri(f1,f2);
const
  rmax=6; limit=10;
  smax=20;
var
  rule:array[1..rmax,1..2] of string[20];
  st,nd,temp:string;
  best,max,i:integer;
  f1,f2:text;
procedure try(now:string;step:integer);
var
  k:integer; temp1:integer;
  stemp:string;
begin
  for k:=1 to max do begin
     if length(now)+length(rule[k,2])-length(rule[k,1])<115 then
       temp1:=pos(rule[k,1],now);
     if temp1<>0 then begin
         stemp:=copy(now,1,temp1-1)+rule[k,2]+copy(now,temp1+length(rule[k,1]),115);
         if stemp=nd then begin
             if step<best then best:=step;
           end
           else begin
             if step<limit then try(stemp,step+1);
         end;
     end;
  end
end;
Begin
  assign(f1,'string.in'); assign(f2,'string.out');
  reset(f1); rewrite(f2);
  readln(f1,temp);
  st:=copy(temp,1,pos(' ',temp)-1);
  nd:=copy(temp,pos(' ',temp)+1,20);
  max:=0;
  while not eof(f1) do begin
    readln(f1,temp);
    max:=max+1;
    rule[max,1]:=copy(temp,1,pos(' ',temp)-1);
    rule[max,2]:=copy(temp,pos(' ',temp)+1,20);
  end;
  best:=limit+1;
  try(st,1);
  if best<limit then writeln(f2,best)
    else writeln(f2,'NO ANSWER!');
  close(f1);close(f2);
End.