oj.uz

Submission #485635

# Submission time Handle Problem Language Result Execution time Memory
485635 2021-11-08T17:31:51 Z inluminas Kangaroo (CEOI16_kangaroo) C++14
0 / 100
 0 ms 204 KB 
#include"bits/stdc++.h"
using namespace std;

#define ll long long
#define endl "\n"
#define fastio ios_base::sync_with_stdio(false)
#define inf LLONG_MAX

const int lmt=2e3+1;
const ll mod=1e9+7;
int n,cf,cs;
bool state[lmt];
ll ans;

ll f(ll cnt){
  if(!cnt) return 1LL;
  ll res=1;
  for(int i=1;i<=cnt;i++) res=(res*i)%mod;
  return res;
}

void solve(){
  for(int i=2;i<=n;i++) state[i]=state[i-1]^1;
  ll o=0,z=0;
  for(int i=3;i<n-1;i++){
    if(state[i]) o++;
    else z++;
  }
  ll stan=(f(o)*f(z))%mod;
  for(int i=1;i<=n;i++){
    for(int j=1;j<=n;j++){
      if(i==cf || i==cs || j==cf || j==cs) continue;
      if((i>cs)!=state[2]) continue;
      if((j>cf)!=state[n-1]) continue;
      if((2==n-1)!=(i==j)) continue;
      ans=(ans+stan)%mod;
    }
  }
  return;
}

int main(){
  fastio;

  cin>>n>>cs>>cf;
  if(n==2){
    cout<<1<<endl;
    return 0;
  }
  state[1]=0;
  solve();
  state[1]=1;
  solve();
  cout<<ans<<endl;
  return 0;
}

Subtask #1
0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Incorrect 0 ms 204 KB Output isn't correct

Subtask #2
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Incorrect 0 ms 204 KB Output isn't correct

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Incorrect 0 ms 204 KB Output isn't correct

Subtask #4
0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Incorrect 0 ms 204 KB Output isn't correct