2875: [Noi2012]随机数生成器 - BZOJ

Description
Input

包含6个用空格分割的m,a,c,X0,n和g，其中a,c,X0是非负整数，m,n,g是正整数。

Output

输出一个数，即Xn mod g
Sample Input

11 8 7 1 5 3

Sample Output
2

快速幂+快速乘

 type
     matrix=array[..,..]of int64;
 var
     a,c,p,x0,n,g:int64;
     x,y:matrix;

 function kc(x,y:int64):int64;
 begin
     if y= then exit();
     kc:=kc(x,y>>);
     kc:=(kc+kc)mod p;
     if y and = then kc:=(kc+x)mod p;
 end;

 operator *(a,b:matrix)c:matrix;
 var
     i,j,k:longint;
 begin
     fillchar(c,sizeof(c),);
     for i:= to  do
         for j:= to  do
             for k:= to  do
                 c[i,k]:=(c[i,k]+kc(a[i,j],b[j,k]))mod p;
 end;

 procedure main;
 begin
     read(p,a,c,x0,n,g);
     x[,]:=;x[,]:=;
     y[,]:=a;y[,]:=c;y[,]:=;
     while n> do
         begin
             if n and = then x:=x*y;
             y:=y*y;
             n:=n>>;
         end;
     writeln((kc(x0,x[,])+x[,])mod p mod g);
 end;

 begin
     main;
 end.