题解 | 数楼梯

#include <iostream>
using namespace std;
#include<vector>
const int N = 998244353;
int way(int n) {
    vector<int>num(n + 1, 0);
    num[1] = 1;
    num[2] = 2;
    for (int i = 3; i <= n; i++) {
        num[i] = (num[i - 1] + num[i - 2]) % N;
    }
    return num[n];
}
int main() {
    int n;
    cin >> n;
    cout << way(n) << endl;
    return 0;
}

// 64 位输出请用 printf("%lld")