Submission #47432

#	Time	Username	Problem	Language	Result	Execution time	Memory
47432		Just_Solve_The_Problem	Tents (JOI18_tents)	C++11	100 / 100	495 ms	71616 KiB

tents

#include <bits/stdc++.h>

using namespace std;

#define pb push_back
#define eb emplace_back
#define ll long long
#define pii pair < int, int >
#define fr first
#define sc second
#define mk make_pair
#define sz(s) (int)s.size()
#define all(s) s.begin(), s.end()
#define ok puts("ok");
#define whatis(x) cerr << #x << " = " << x << endl;
#define pause system("pause");
#define random rand() ^ (rand() << 5)

const int N = (int)3e3 + 7;
const int inf = (int)1e9 + 7;
int mod = 1e9 + 7;

ll add(ll a, ll b) {
  a += b;
  if (a > mod) a -= mod;
  return a;
}

ll mult(ll a, ll b) {
  return a * b % mod;
}

int n, m;
ll dp[N][N];

main() {
  for (int i = 0; i < N; i++)
    dp[0][i] = dp[i][0] = 1;
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      ll &res = dp[i][j];
      if (j > 1)
        res = add(res, mult(dp[i - 1][j - 2], j * (j - 1) / 2));
      res = add(res, mult(dp[i - 1][j - 1], 4 * j));
      if (i > 1)
        res = add(res, mult(dp[i - 2][j - 1], j * (i - 1)));
      res = add(res, dp[i - 1][j]);
    }
  }
  printf("%lld", (dp[n][m] - 1 + mod) % mod);
}

Compilation message (stderr)

tents.cpp:36:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main() {
      ^
tents.cpp: In function 'int main()':
tents.cpp:39:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &n, &m);
   ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52