848E - Days of Floral Colours - CodeForces Solution

#include<iostream>
#define mod 998244353 
#define int long long
using namespace std;
int flowerColorsCount;
int intermediateResults[16] = { 0, 4, 8, -1, 16, -10, 4, -12, -48, 26, -44, 15, -16, -4, -4, -1 };
int beautySums[16] = { 0, 0, 0, 24, 4, 240, 204, 1316, 2988, 6720, 26200, 50248, 174280, 436904, 1140888, 3436404 };
main() {
	cin >> flowerColorsCount;
	for (int colorIndex = 16; colorIndex <= flowerColorsCount; colorIndex++) {
		int intermediateSum = 0;
		for (int resultIndex = 0; resultIndex < 16; resultIndex++) intermediateSum = (intermediateSum + 1ll * intermediateResults[(colorIndex - resultIndex - 1) & 15] * beautySums[resultIndex] % mod) % mod;
		beautySums[colorIndex & 15] = intermediateSum;
	} cout << (beautySums[flowerColorsCount & 15] + mod) % mod;
}/*1694990382.9800775*/