Submission #67790842

---

Source Code Expand

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

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef double db;

const int mod = 998244353;

int add(int a, int b)
{
	return a + b < mod ? a + b : a + b - mod;
}

void updAdd(int& a, int b)
{
	a += b;
	if (a >= mod)
		a -= mod;
}

int sub(int a, int b)
{
	return a - b >= 0 ? a - b : a - b + mod;
}

void updSub(int& a, int b)
{
	a -= b;
	if (a < 0)
		a += mod;
}

int mult(int a, int b)
{
	return (LL)a * b % mod;
}

int binpow(int a, LL n)
{
	int res = 1;
	while (n)
	{
		if (n & 1)
			res = mult(res, a);
		a = mult(a, a);
		n /= 2;
	}
	return res;
}

const int N = 1 << 20;

int inv[N], fact[N], ifact[N];

void init()
{
	inv[1] = 1;
	FOR(i, 2, N)
	{
		inv[i] = mult(mod - mod / i, inv[mod % i]);
	}
	fact[0] = ifact[0] = 1;
	FOR(i, 1, N)
	{
		fact[i] = mult(fact[i - 1], i);
		ifact[i] = mult(ifact[i - 1], inv[i]);
	}
}

int C(int n, int k)
{
	if (k < 0 || k > n)
		return 0;
	return mult(fact[n], mult(ifact[n - k], ifact[k]));
}

/*int H(int n, int k)
{
	return C(n + k - 1, n - 1);
}*/

template<typename T>
void updMin(T& a, T b)
{
	a = min(a, b);
}

template<typename T>
void updMax(T& a, T b)
{
	a = max(a, b);
}

int main()
{
	ios::sync_with_stdio(0); 
	cin.tie(0);
	init();
	int h, w;
	cin >> h >> w;
	if (h % 2 == 0)
	{
		cout << "0\n";
		return 0;
	}
	if (w % 2 == 1)
	{
		int ans = 0;
		for (int d = 1; d <= h; d += 2)
		{
			if (gcd(d, w) == 1)
				updAdd(ans, C(h, (h + d) / 2));
		}
		ans = mult(ans, 2);
		cout << ans << "\n";
		return 0;
	}
	h *= 2;
	int ans = 0;
	for (int d = 0; d <= h; d += 2)
	{
		if (gcd(d, w) == 2)
			updAdd(ans, C(h, (h + d) / 2));
	}
	ans = mult(ans, 2);
	cout << ans << "\n";
	return 0;
}

Submission Info

Judge Result