Submission #1118275

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118275		vjudge1	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	47 ms	33176 KiB

kangaroo

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int mod = 1e9 + 7;

int dp[2100][2100];

signed main(){
    int n, st, fs; 
    cin >> n >> st >> fs;
    dp[1][1] = 1;
    for (int i = 2; i <= n; i++){
        int cnt = 0;
        if(i > st) cnt++;
        if(i > fs) cnt++;
        for(int j=1;j<=n;++j){
            if(i == st || i == fs){
                dp[i][j] = (dp[i][j] + dp[i-1][j] + dp[i-1][j-1]) % mod;
                continue;
            }
            dp[i][j] = (((dp[i][j] + ((dp[i-1][j+1] * j) % mod))%mod) + ((((dp[i-1][j-1] * (j - cnt)) % mod) + mod) % mod));
        }
    }
    cout << dp[n][1];
}

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