Submission #65681312

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Source Code Expand

#include <iostream>
using namespace std;
#define ll long long
const ll Mmod = 998244353;
ll a, b, c, d, ans, w1, t1, w2;

ll Qpow(ll a, ll b) {
	if (b == 0) return 1ll;
	ll t = Qpow(a, b/2);
	t = t * t % Mmod;
	if (b % 2 == 1) t = t * a % Mmod;
	return t;
}

ll C(int n, int m) { // C(n,m)
	ll a = 1, b = 1;
	for(int i = 1; i <= m; i++) b = b * i % Mmod;
	for(int i = n-m+1; i <= n; i++) a = a * i % Mmod;
	return a * Qpow(b, Mmod - 2) % Mmod;
}

int main ()
{
	cin >> a >> b >> c >> d;
	w1 = 1;
	w2 = C(a+b+c, b);
	ll x = a+b+c, y = a+c;
	ans = (ans + w1 * w2 % Mmod) % Mmod;
	for(ll c1 = 1; c1 <= c; c1++) {
		w1 = w1 * (d+c1-1) % Mmod * Qpow(c1, Mmod-2) % Mmod;
		w2 = w2 * y % Mmod * Qpow(x, Mmod-2) % Mmod;
		x--, y--;
		ans = (ans + w1 * w2 % Mmod) % Mmod;
	}
	cout << ans << endl;
	return 0;
}

Submission Info

Judge Result