Submission #1118230

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118230		vjudge1	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	16 ms	31584 KiB

kangaroo

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define FORI(i, n) for(ll i = 0; i < n; i++)
#define FOR(i, n) for(ll i = 1; i <= n; i++)
typedef vector<ll> vl; 
typedef set<ll> setl;
#define ff first
#define ss second    
#define all(v) v.begin(), v.end() 
#define pll pair<ll, ll> 
#define db double
#define nll cout << "\n"
#define nl "\n"
#define sync ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);

const ll mod =  1e9 + 7;
const int MAX = 2000 + 5;

ll n, m, k, res;
ll dp[MAX][MAX];
void solve(){
    cin >> n >> m >> k;
    dp[1][1] = 1;
    for(ll i = 2; i <= n; i++){
        FOR(j, i){
            if(i == m|| i == k){
                dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % mod;
            }
            else{
                dp[i][j] = ((dp[i - 1][j - 1] * (j - (i > m) - (i > k)) ) % mod + (dp[i - 1][j + 1] * j) % mod) % mod;
            }
        }
    }
    cout << dp[n][1] % mod;
}
signed main(){  
    // freopen("input.txt","r",stdin);
    // freopen("output.txt","w",stdout);
    sync;
    ll t = 1;
    // cin >> t;
    FOR(i, t){
        // cout << "Case #" << i << ": ";
        solve();
    }
}

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