Submission #1007209

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Source Code Expand

#include <algorithm>
#include <cassert>
#include <cstring>
#include <iostream>

using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define TRACE(x) cout << #x << " = " << x << endl
#define _ << " _ " <<

typedef long long llint;

const int mod = 1e9 + 7;
const int MAX = 5050;

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

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

inline int mul(int a, int b) {
  return llint(a)*b % mod;
}

int c[MAX][MAX];
int g[MAX][MAX];

int f(int A, int B, int C) {
  if (B % 2) return 0;

  int kb = B / 2;
  int ans = 0;
  REP(ka, A + 1) {
    int kc = A - ka;
    for (int kd = 0; kc + kd*3 <= C; ++kd) {
      int ways = 1;
      ways = mul(ways, c[ka+kb+kc+kd][ka]);
      ways = mul(ways, c[kb+kc+kd][kb]);
      ways = mul(ways, c[kc+kd][kc]);
      ways = mul(ways, g[kb][C-kc-kd*3]);
      ans = add(ans, ways);
    }
  }
  return ans;
}

int main(void) {
  REP(i, MAX) {
    c[i][0] = 1;
    FOR(j, 1, i+1)
      c[i][j] = add(c[i-1][j], c[i-1][j-1]);
  }

  REP(i, MAX) {
    REP(j, MAX) {
      if (j == 0) { g[i][j] = 1; continue; }
      if (i == 0) continue;
      g[i][j] = add(g[i][j-1], g[i-1][j]);
    }
  }
  
  int N, A, B, C;
  scanf("%d %d %d %d", &N, &A, &B, &C);
  printf("%d\n", f(A, B, C));
  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:68:39: 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