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[0..30,0..30] 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),0);
 for i:=0 to m-1 do
  for j:=0 to m-1 do
   for k:=0 to m-1 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>0 do
  begin
  if k and 1=1 then power:=mul(power,a);
  a:=mul(a,a);k:=k>>1;
  end;
 end;
begin
 readln(n,m,p);
 readln(s);
 for j:=0 to m-1 do
  zero[i,i]:=1;
 for j:=0 to m-1 do
  for ch:='0' to '9' do
   begin
   ts:=copy(s,1,j)+ch;
   for k:=j+1 downto 0 do
    if copy(s,1,k)=copy(ts,j-k+2,k) then break;
   inc(a[j,k]);
   end;
 ans:=power(a,n);
 for i:=0 to m-1 do sum:=(sum+ans[0,i]) mod p;
 writeln(sum);
end.
                          

等我改一下的我的程序再发上来……