BZOJ 1002: [FJOI2007]轮状病毒

/*
BZOJ 1002: [FJOI2007]轮状病毒

基尔霍夫矩阵 + 高精
题解看的我一脸懵逼。。只能记结论了
*/
#include <cstdio>
#include <iostream>

#define L 101
struct Int { int c[L], l; };

Int operator - (Int A, Int B)
{
register int i; A.c[1] += 2;
for (i = 1; A.c[i] >= 10; ++ i)
A.c[i] %= 10, ++ A.c[i + 1];
for (i = 1; i <= A.l; ++ i)
{
A.c[i] -= B.c[i];
if (A.c[i] < 0)
A.c[i] += 10, -- A.c[i + 1];
}
for (; !A.c[A.l]; -- A.l);
return A;
}

Int operator * (Int A, int b)
{
register int i;
for (i = 1; i <= A.l; ++ i) A.c[i] *= b;
for (i = 1; i <= A.l; ++ i)
A.c[i + 1] += A.c[i] / 10, A.c[i] %= 10;
if (A.c[A.l + 1]) ++ A.l;
return A;
}
#define Max 101
Int f[Max];

int Main ()
{
int N; register int i; scanf ("%d", &N);
f[1].l = f[2].l = 1; f[1].c[1] = 1, f[2].c[1] = 5;
for (i = 3; i <= N; ++ i)
f[i] = (f[i - 1] * 3) - f[i - 2];
for (i = f
.l; i; -- i)
printf ("%d", f
.c[i]);
return 0;
}
int ZlycerQan = Main ();
int main (int argc, char *argv[]) {;}