Submission #310455

#	Time	Username	Problem	Language	Result	Execution time	Memory
310455		VROOM_VARUN	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	28 ms	31744 KiB

kangaroo

/*
ID: varunra2
LANG: C++
TASK: kangaroooo
*/

#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

const int N = 2005;

ll dp[N][N];

int main() {
  // #ifndef ONLINE_JUDGE
  // freopen("kangaroooo.in", "r", stdin);
  // freopen("kangaroooo.out", "w", stdout);
  // #endif
  cin.sync_with_stdio(0);
  cin.tie(0);

  int n, a, b;
  cin >> n >> a >> b;

  dp[1][1] = 1;

  for (int i = 2; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (i == a or i == b)
        dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % MOD;
      else {
        dp[i][j] = dp[i - 1][j + 1] * j;
        dp[i][j] += dp[i - 1][j - 1] * (max(0, (j - (i > a) - (i > b))));
        dp[i][j] %= MOD;
      }
    }
  }

  cout << dp[n][1] << '\n';

  return 0;
}

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49