Submission #699863

#	Time	Username	Problem	Language	Result	Execution time	Memory
699863		Sam_a17	Kangaroo (CEOI16_kangaroo)	C++17	0 / 100	1 ms	340 KiB

kangaroo

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
  
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
  
#define sz(x) (int)x.size()
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt __builtin_popcount
  
#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
#define ll long long

void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
  
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[],V n) {cerr << "["; for(int i = 0; i < n; i++) {print(v[i]); cerr << " "; } cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
  
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
  
// for random generations
// mt19937 myrand(chrono::steady_clock::now().time_since_epoch().count());
mt19937 myrand(373);
  
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
  
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
  fastIO();
  
  if(str == "input") {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
  } else {
    // freopen("skis.in", "r", stdin);
    // freopen("skis.out", "w", stdout);
  }
}
// Indexed Set  
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const long long mod = 1e9 + 7;
const int N = 2e3 + 10;
long long dp[N][N];
int n, s, e;

long long add(long long a, long long b) {
  return (a + b) % mod;
}

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

long long sub(long long a, long long b) {
  return (a - b + 2 * mod) % mod;
}

void solve_() {
  cin >> n >> s >> e;

  dp[1][1] = 1;
  
  for(int i = 1; i < n; i++) {
    for(int j = 1; j <= i; j++) {
      if((i + 1) == s || (i + 1) == e) {
        dp[i + 1][j] = add(dp[i + 1][j], dp[i][j]);
        dp[i + 1][j + 1] = add(dp[i + 1][j + 1], dp[i][j]);
      } else {
        dp[i + 1][j + 1] = add(dp[i + 1][j + 1], mult(dp[i][j], j + 1 - (j > s) - (j > e)));
        if(j >= 2) {
          dp[i + 1][j - 1] = add(dp[i + 1][j - 1], mult(dp[i][j], j - 1));
        }
      }
    }
  }

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

int main() {
  setIO();
 
  auto solve = [&](int test_case)-> void {
    for(int i = 1; i <= test_case; i++) {
      solve_();
    }
  };
  
  int test_cases = 1;
  // cin >> test_cases;
  solve(test_cases);
  
  return 0;
}

Compilation message (stderr)

kangaroo.cpp: In function 'void setIO(std::string)':
kangaroo.cpp:70:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |     freopen("input.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
kangaroo.cpp:71:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |     freopen("output.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 30
• Subtask 3: 0 / 15
• Subtask 4: 0 / 49