pku2185 Milking Grid 2012-01-11

 1 Program stone;
 2 var i,j,k,n,m,lc,rc:longint;
 3     s:array[1..10000,1..100]of char;
 4     b:array[1..10000,1..100]of longint;
 5  function gcd(x,y:longint):longint;
 6  var i,j,k:longint;
 7   begin
 8     if x>y then begin i:=x;j:=y;end
 9            else begin i:=y;j:=x;end;
10     while i mod j<>0 do
11      begin
12        k:=i-j;
13        if k<j then begin i:=j;j:=k;end
14               else i:=k;
15      end;
16     gcd:=x*y div j;
17   end;
18 Begin
19  assign(input,‘input.in‘);reset(input);
20   readln(n,m);
21   for i:=1 to n do
22    begin
23    for j:=1 to m do read(s[i,j]);
24      readln;
25    end;
26   lc:=1;rc:=1;
27   for i:=1 to n do
28    begin
29      k:=0;b[i,1]:=0;
30      for j:=2 to m do
31       begin
32         while (k>0)and(s[i,j]<>s[i,k+1]) do k:=b[i,k];
33         if s[i,j]=s[i,k+1] then inc(k);
34         b[i,j]:=k;
35       end;
36      k:=m-b[i,m];
37      lc:=gcd(lc,k);
38    end;
39   if lc>m then lc:=m;
40   fillchar(b,sizeof(b),0);
41   for i:=1 to m do
42     begin
43       k:=0;b[1,i]:=0;
44       for j:=2 to n do
45        begin
46          while (k>0)and(s[j,i]<>s[k+1,i]) do k:=b[k,i];
47          if s[j,i]=s[k+1,i] then inc(k);
48          b[j,i]:=k;
49        end;
50       k:=n-b[n,i];
51       rc:=gcd(rc,k);
52     end;
53    if rc>m then rc:=m;
54    write(lc*rc);
55 end.
56 
57