Paperfolding
https://vjudge.net/contest/387654#problem/I
算数学期望
对折和切刀都会使数量翻倍
横着切刀和上下对着效果相同,竖着切刀和左右对折效果相同
#include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<bitset> #include<cassert> #include<cctype> #include<cmath> #include<cstdlib> #include<ctime> #include<deque> #include<iomanip> #include<list> #include<map> #include<queue> #include<set> #include<stack> #include<vector> #include <vector> #include <iterator> #include <utility> #include <sstream> #include <limits> #include <numeric> #include <functional> using namespace std; #define gc getchar() #define mem(a) memset(a,0,sizeof(a)) #define ios ios::sync_with_stdio(false);cin.tie(0);cout.tie(0); typedef long long ll; typedef unsigned long long ull; typedef long double ld; typedef pair<int,int> pii; typedef char ch; typedef double db; const double PI=acos(-1.0); const double eps=1e-6; const int inf=0x3f3f3f3f; const int maxn=1e5+10; const int maxm=100+10; const int N=1e6+10; const int mod=1e9+7; ll MOD = 998244353; ll P(ll k , ll n) { ll base = 1; k %= MOD; while(n) { if(n & 1) { base = base * k % MOD; } k = k * k % MOD; n >>= 1; } return base; } int main() { int T = 0; ll n = 0 , ans = 0; cin >> T; while(T--) { cin >> n; ans = 2 * P(3 , n) % MOD; ll temp = P(2 , n); ans *= P(temp , MOD-2); ans %= MOD; ans += 1 + temp; ans %= MOD; cout << ans <<endl; } return 0; }