Submission #1089586

#	Time	Username	Problem	Language	Result	Execution time	Memory
1089586		BF001	Kangaroo (CEOI16_kangaroo)	C++17	0 / 100	1 ms	348 KiB

kangaroo

#include<bits/stdc++.h>
using namespace std;
 
#define int long long
#define N 2005

int md = 1e9 + 7, dp[N][N], cf, cs, n;
 
signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
 
    cin >> n >> cs >> cf;
    dp[1][1] = 1;
    for (int i = 2; i <= n; i++){
        for (int j = 1; j <= n; j++){
            if (i == cs || i == cf){
                dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % md;
                continue;
            }
            dp[i][j] = dp[i - 1][j - 1] * (j - (j > cs) - (j > cf)) % md;
            dp[i][j] = dp[i - 1][j + 1] * j % md;
        }
    }    

    cout << dp[n][1];
 
    return 0;
}

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