Submission #34399458

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

#ifdef B01
#include "deb.h"
#else
#define deb(...)
#endif

const int N = (int) 5e6 + 9;
const long long md = (long long) 998244353;

long long iv[N], f1[N], f2[N];

long long C(long long n, long long k) {
  return (long long) f1[n] * f2[n - k] % md * f2[k] % md;
}

void bldI() {
  iv[1] = 1;
  for(long long i = 2; i < N; i++) {
    iv[i] = md - md / (long long) i * iv[md % i] % md;
  }
}

void bldF() {
  f1[0] = f2[0] = 1;
  for(long long i = 1; i < N; i++) {
    f1[i] = (long long) f1[i - 1] * i % md;
    f2[i] = (long long) f2[i - 1] * iv[i] % md;
  }
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  bldI();
  bldF();
  long long r, g, b, k;
  cin >> r >> g >> b >> k;
  long long n = r + g + b;
  r -= k; g -= k; n -= k;
  long long ans = C(n, k);
  n -= k;
  long long z = 0;
  for (long long i = 0; i <= min(r, g); i++) {
    if (i & 1) {
      z -= C(n - i, i) * C(n - i - i, r - i) % md * C(n - i - r, g - i) % md * C(n - r - g, b) % md;
      z %= md;
      z += md;
      z %= md;
    } else {
      z += C(n - i, i) * C(n - i - i, r - i) % md * C(n - i - r, g - i) % md * C(n - r - g, b) % md;
      z %= md;
    }
  }
  cout << ans * z % md << '\n';
  return 0;
}
// G

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Judge Result