UVA 11885 - Number of Battlefields（斐波那契）

#include <stdio.h>
#include <string.h>

const long long MOD = 987654321;
int p;

struct mat {
	long long v[2][2];
	mat() {memset(v, 0, sizeof(v));}
	mat operator *(mat c) {
		mat ans;
		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < 2; j++) {
				for (int k = 0; k < 2; k++) {
					ans.v[i][j] = (ans.v[i][j] + v[i][k] * c.v[k][j] % MOD) % MOD;
    			}
   			}
  		}
  		return ans;
 	}
 	mat operator^(int k) {
 		mat x = *this, ans;
 		ans.v[0][0] = ans.v[1][1] = 1;
 		while (k) {
 			if (k&1)
 				ans = ans * x;
			x = x * x;
			k >>= 1;
   		}
   		return ans;
  	}
};

int main() {
	while (~scanf("%d", &p) && p) {
		if(p % 2) {printf("0\n"); continue;}
		mat pri;
		pri.v[0][0] = pri.v[0][1] = pri.v[1][0] = 1;
		pri = pri^(p - 4);
		printf("%lld\n",(pri.v[0][0] - ((long long)p / 2 - 1) + MOD) % MOD);
 	}
	return 0;
}