HDU 1021－Fibonacci Again

题目大意：F(0) = 7, F(1) = 11, F(n) = F(n-1) + F(n-2) (n>=2).求F（n）是不是能被 3 整除

解题思路：（a＋b）％c ＝ （a％c ＋ b％c）％c

#include <stdio.h>#include <iostream>using namespace std;int main() {    long long int n;    while(scanf("%lld", &n) != EOF) {        long long int x1 = 1, x2 = 2, s = 0;        if(n == 0)            s = 1;        else if(n == 1)            s = 2;        else              for(int i = 1; i < n; i++) {                s = (x1 + x2)%3;                x1 = x2;                x2 = s;            }        if(s == 0)            cout << "yes" << endl;        else             cout << "no" << endl;    }}