洛谷 P1019 单词接龙

P1019 单词接龙

var a:array[1..21] of string;  b:array[1..21] of integer;i,n,x,max:longint;   ch:char;function min(a,b:longint):longint;begin  if a>b then exit(b) else exit(a);end;function f(a,b:string):string;var l1,l2,i,k:longint;  s1,s2:string;begin  l1:=length(a);  l2:=length(b);  f:='';  for i:=1 to min(l1,l2) do  begin    s1:=copy(a,l1-i+1,i);    s2:=copy(b,1,i);    if s1=s2      then exit(copy(a,1,l1-i)+b);  end;end;procedure dfs(s,s2:string);var s1:string;i,ans1:longint;begin  for i:=1 to n do  begin    if ((pos(a[i],s2)>0) or (pos(s2,a[i])>0)) and (s2<>a[i])      then continue;    if (b[i]<2)      then      begin        s1:=f(s,a[i]);        if s1<>''          then          begin            inc(b[i]);            ans1:=length(s1);            if ans1>max              then max:=ans1;            dfs(s1,a[i]);            dec(b[i]);          end;      end;  end;end;begin  readln(n);  for i:=1 to n do    readln(a[i]);  readln(ch);  //writeln(f('aba','aa'));  for i:=1 to n do    if a[i][1]=ch      then      begin        //max:=length(a[i]);        inc(b[i]);        dfs(a[i],a[i]);        dec(b[i]);      end;  writeln(max);end.