HNOI2008 GT 考试

我不明白为什么是DP,我感觉和vijos的核电站问题（https://www.vijos.org/p/1232）差不多啊

这是别人的题解：http://www.cnblogs.com/Skywalker-Q/archive/2011/03/17/1987395.html

 type matrix=array[..,..] of longint;
 var n,m,i,j,k,p,sum:longint;
     a,ans,zero:matrix;
     s,ts:string;
     ch:char;
 function mul(a,b:matrix):matrix;
  var i,j,k:longint;
  begin
  fillchar(mul,sizeof(mul),);
  for i:= to m- do
   for j:= to m- do
    for k:= to m- do
     mul[i,j]:=(mul[i,j]+a[i,k]*b[k,j]) mod p;
  end;
 function power(a:matrix;k:longint):matrix;
  begin
  power:=zero;
  while k> do
   begin
   if k and = then power:=mul(power,a);
   a:=mul(a,a);k:=k>>;
   end;
  end;
 begin
  readln(n,m,p);
  readln(s);
  for j:= to m- do
   zero[i,i]:=;
  for j:= to m- do
   for ch:='' to '' do
    begin
    ts:=copy(s,,j)+ch;
    for k:=j+ downto  do
     if copy(s,,k)=copy(ts,j-k+,k) then break;
    inc(a[j,k]);
    end;
  ans:=power(a,n);
  for i:= to m- do sum:=(sum+ans[,i]) mod p;
  writeln(sum);
 end.
                           

等我改一下的我的程序再发上来……