题目链接：https://cn.vjudge.net/problem/HDU-2045
找规律
代码
#include <cstdio>
long long num[51][2];
int n;
int main(void){
num[0][0]=2; num[0][1]=0;
for (int i=0; i<50; i++){
num[i+1][0]+=num[i][0]+num[i][1]*2;
num[i+1][1]+=num[i][0];
}
while (scanf("%d", &n)==1 && n){
if (n>=3) printf("%lld\n", 3*(num[n-3][0]+2*num[n-3][1]));
else printf("%d\n", (n==2)?6:3);
}
return 0;
}
| 1504kB | 333 | G++ | 2018-01-17 13:39:25 |