取名不要太长，像我这样刚刚好 · 发布于 2025-02-19 · 浏览 490 回复 0

unsigned long long F[75] = {0, 1, 2, 4};
for (int i = 4; i <= 73; i++)
	F[i] = F[i - 3] + F[i - 2] + F[i - 1];
for (int n; scanf("%d", &n) != EOF;)
	printf("%llu\n", F[n]);
return 0;