Submission #1986410

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Source Code Expand

#include<stdio.h>
#include<vector>
#include<algorithm>
using namespace std;
typedef long long ll;
ll mod = 1000000007;
#define SIZE 100000
ll inv[SIZE + 1];
ll kai[SIZE + 1];
ll invkai[SIZE + 1];
void invinit()
{
	inv[1] = 1;
	for (int i = 2; i <= SIZE; i++)
	{
		inv[i] = mod - (mod / i)*inv[mod%i] % mod;
	}
	kai[0] = invkai[0] = 1;
	for (int i = 1; i <= SIZE; i++)
	{
		kai[i] = kai[i - 1] * i%mod;
		invkai[i] = invkai[i - 1] * inv[i] % mod;
	}
}
ll com(ll a, ll b)
{
	if (b < 0 || a < b)return 0;
	return (invkai[b] * invkai[a - b]) % mod*kai[a] % mod;
}
int main()
{
	invinit();
	int n, a, b, c;
	scanf("%d%d%d%d", &n, &a, &b, &c);
	if (b % 2 != 0)
	{
		printf("0\n");
		return 0;
	}
	ll ans = 0;
	for (int i = 0; i <= c / 3; i++)
	{
		for (int j = 0; j <= min(a, c - i * 3); j++)
		{
			ll t = com(a + b / 2 + i, i)*com(a + b / 2, a) % mod*com(a, j) % mod;
			if (b > 0)t *= com(c - i * 3 - j + b / 2 - 1, b / 2 - 1);
			else if (c != i * 3 + j)t = 0;
			ans = (ans + t) % mod;
		}
	}
	printf("%lld\n", ans);
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:34:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d%d", &n, &a, &b, &c);
                                   ^

Judge Result