2
3
ABCD
BCDFF
BRCD
2
rose
orchid

2
2 

还是KMP，先在第一个串中枚举串，之后考察它是否是其它串的'正/逆'子串。

Program P1226;
const
   maxn=100;
   maxt=10;
var
   tt,n,m,i,j,k,ans:longint;
   flag:boolean;
   a:array[1..maxn] of string;
   p:string;
   next:array[1..maxn] of longint;

function kmp(a,b:string):boolean;
var
   i,j,n,m:longint;
begin
   i:=1;j:=0;next[1]:=0;
   n:=length(a); m:=length(b);
   while (i<m) do
   begin
      if (j=0) or (b[i]=b[j]) then
      begin
         inc(i);inc(j);
         if (b[i]<>b[j]) then next[i]:=j else next[i]:=next[j];
      end else j:=next[j];
   end;

   i:=0;j:=0;
   while (i<=n) and (j<=m) do
   begin
      if (j=0) or (a[i]=b[j]) then
      begin
         inc(i);inc(j);
      end else j:=next[j];
   end;
   if (j>m) then exit(true);
   exit(false);
end;
function ob_s(a:string):string;
var
   i,j,n:longint;
begin

   ob_s:=''; n:=length(a);
   for i:=n downto 1 do ob_s:=ob_s+a[i];
end;
function compare(a,b:string):boolean;
var
   n,m:longint;
begin
   n:=length(a);m:=length(b);
   if (n<>m) then exit(n<m);
   for i:=1 to n do
      if a[i]<>b[i] then exit(a[i]<b[i]);
   exit(false);
end;


begin
   readln(tt);
   while (tt>0) do
   begin
      ans:=0;
      readln(n);
      for i:=1 to n do readln(a[i]);

      for i:=1 to length(a[1]) do
         for j:=i to length(a[1]) do
         begin
            p:=copy(a[1],i,j-i+1);
            flag:=true;
            for k:=2 to n do
            begin
               if not((kmp(a[k],p) or kmp(a[k],ob_s(p)))) then
               begin
                  flag:=false; break;
               end;
            end;
            if flag and (length(p)>ans) then ans:=length(p);


         end;

      writeln(ans);
      dec(tt);
   end;
end.