题解

#include <bits/stdc++.h>
using namespace std;

long long a[100010];

int main() {
	int n;
	cin >> n;
	a[1] = 1;
	a[2] = 2;
	for (int i = 3; i <= n; i++) {
		a[i] = a[i - 1] + a[i - 2];
	}
	cout << a[n];
}

就是骨牌铺法