P1990 覆盖墙壁

题目链接：

#include <bits/stdc++.h>

using namespace std;
using i64 = long long;

const int N = 1e6 + 10;
int f[N], pre[N];

int main()
{
	ios::sync_with_stdio(false), cin.tie(nullptr);
	int n;
	cin >> n;
	pre[0] = f[0] = 1;
	for (int i = 1; i <= n; i++) {
		f[i] = (i64)((i >= 1 ? pre[i - 1] : 0) + (i >= 3 ? pre[i - 3] : 0)) % 10000;
		pre[i] = (i64)(pre[i - 1] + f[i]) % 10000;
	}
	cout << f[n];
	return 0;
}