杭电oj 2045 不容易系列之（3）—— LELE的RPG难题 C语言

#include
 
void main()
{
	int n, i;
	long long arr[51];
	while (~scanf_s("%d", &n))
	{
		arr[0] = 3, arr[1] = 6, arr[2] = 6;
		for (i = 3; i < n; i++)arr[i] = arr[i - 1] + arr[i - 2] * 2;
		printf("%lld\n", arr[n - 1]);	
	}
}