Submission #1202203

#	Time	Username	Problem	Language	Result	Execution time	Memory
1202203		SyedSohaib_123	Kangaroo (CEOI16_kangaroo)	C++20	100 / 100	43 ms	86600 KiB

kangaroo

#include <bits/stdc++.h>

#define append push_back
#define int long long

using namespace std;

const int N=2e3+10;
const int mod=1e9+7;
int dp[N][N][5];
void solve(){
    int n,s,e;
    cin>>n>>s>>e;
    dp[1][1][s==1 or e==1] = 1;
    for(int i=2;i<=n;i++){
        for(int j=1;j<=i;j++){
            if(i==s or i==e){
                for(int k=1;k<=2;k++) dp[i][j][k]=(dp[i-1][j-1][k-1]+dp[i-1][j][k-1])%mod;
            }
            else{
                for(int k=0;k<=2;k++) dp[i][j][k]=(dp[i-1][j-1][k]*(j-k)*(j>=k)+dp[i-1][j+1][k]*j)%mod;
            }
        }
    }
    cout<<dp[n][1][2];
}

signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int T = 1;
    // cin >> T;
    while (T--) 
        solve();
}

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