Submission #799503

#	Time	Username	Problem	Language	Result	Execution time	Memory
799503		manizare	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	32 ms	31956 KiB

kangaroo

#include <bits/stdc++.h>  
#define pii pair <int,int>  
#define F first  
#define S second  
#define all(a) a.begin(),a.end()  
#define pb push_back 
#define int long long 
using namespace std ;

const int maxn = 2020 , inf  = 1e18 , mod = 1e9 + 7 ;  
int dp[maxn][maxn] , a[maxn] ;
signed main(){ 
  ios::sync_with_stdio(0);cin.tie(0);cout.tie(0) ;
  int n , s , e ;
  cin >> n >> s >> e ;
  dp[0][0] = 1 ;
  for(int i =1 ;i <= n ; i++){
    for(int j = 1; j <= n ; j++){
      int t = (s < i) + (e <i ) ;
      if(i!=s && i!=e){
        dp[i][j] = (dp[i-1][j-1] *(j-t) % mod + dp[i-1][j+1] * j % mod )%mod ;
        continue ;
      }
      dp[i][j] = (dp[i-1][j-1] + dp[i-1][j])%mod ;
    }
  }
  cout << dp[n][1] ;
} 
/* 
 
*/

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