Submission #1005073

#	Time	Username	Problem	Language	Result	Execution time	Memory
1005073		erering	Kangaroo (CEOI16_kangaroo)	C++17	6 / 100	2066 ms	348 KiB

kangaroo

#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define pb push_back
#define ll long long
#define int long long
const long long inf=1e18;
const int MOD=1e9+7;
const int N=41;
int n,cs,cf,ans=0;
bool s[N];
void func(int i,int cnt,bool flag){
    if(cnt==n){
        if(i==cf){
            ans++;
            ans%=MOD;
        }
        return;
    }
    if(flag){
        for(int j=i+1;j<=n;j++){
            if(!s[j]){
                if(j==cf && cnt<n-1)continue;
                s[j]=1;
                cnt++;
                func(j,cnt,0);
                cnt--;
                s[j]=0;
            }
        }
    }
    else{
        for(int j=i-1;j>0;j--){
            if(!s[j]){
                if(j==cf && cnt<n-1)continue;
                s[j]=1;
                cnt++;
                func(j,cnt,1);
                cnt--;
                s[j]=0;
            }
        }
    }
}
signed main()
{
   ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
   cin>>n>>cs>>cf;
   s[cs]=1;
   func(cs,1,0);
   for(int i=0;i<=n;i++)s[i]=0;
   s[cs]=1;
   func(cs,1,1);
   cout<<ans;
}

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