Submission #443571

#	Time	Username	Problem	Language	Result	Execution time	Memory
443571		keta_tsimakuridze	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	22 ms	24000 KiB

kangaroo

#include<bits/stdc++.h>
#define f first
#define s second
#define int long long
using namespace std;
const int N=5005,mod=1e9+7;
int t,n,st,en,dp[N][N];
main(){
	cin>>n>>st>>en;
	dp[1][1] = 1;
	for(int i=2;i<=n;i++) {
		for(int j=1;j<=i;j++) {
			if(i==st || i==en) {
				dp[i][j] = (dp[i-1][j-1] + dp[i-1][j])%mod; 
			}
			else {
				dp[i][j] = (dp[i-1][j+1]*j%mod + dp[i-1][j-1] * (j - (st<i) - (en<i))%mod)%mod;
			}
		}
	}
	cout<<dp[n][1];
}

Compilation message (stderr)

kangaroo.cpp:8:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    8 | main(){
      | ^~~~

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