Submission #1001101

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using D = double;
using uint = unsigned int;

#ifdef WIN32
    #define LLD "%I64d"
#else
    #define LLD "%lld"
#endif

#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second

const int maxn = 5005;
const int MOD = 1000000007;

int cnk[maxn][maxn];
int A, B, C;
int n;

ll get(ll a, ll b)
{
    if (a == 0 && b > 0) return 0;
    if (a == 0 && b == 0) return 1;
    return cnk[a + b - 1][a - 1];
}

ll calc(ll a, ll b, ll c, ll d)
{
//     cout << "calc " << a << ' ' << b << ' ' << c << ' ' << d << ' ' << endl;
    if (d < 0) return 0;
    if (a + b + c + d > n) return 0;
    return (((ll)cnk[a + b][b] * cnk[a + b + c][c]) % MOD * cnk[a + b + c + d][d]) % MOD;
}

int main()
{
    scanf("%d%d%d%d", &n, &A, &B, &C);
    if (B % 2 == 1)
    {
        cout << 0 << endl;
        return 0;
    }
    cnk[0][0] = 1;
    for (int i = 1; i <= n; i++)
    {
        cnk[i][0] = 1;
        for (int j = 1; j <= i; j++) cnk[i][j] = (cnk[i - 1][j - 1] + cnk[i - 1][j]) % MOD;
    }
    ll answer = 0;
    for (int x = 0; x <= C; x++)
    {
        for (int y = 0; 3 * y + x <= C; y++)
        {
            ll curans = calc(B / 2, y, C - 3 * y - x, A - (C - 3 * y - x));
//             cout << x << ' ' << y << ' ' << curans << endl;
            curans = ((ll)curans * get(B / 2, x)) % MOD;
//             cout << curans << endl;
            answer = (answer + curans) % MOD;
        }
    }
    cout << answer << endl;
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:46:38: 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