Submission #741057

#	Time	Username	Problem	Language	Result	Execution time	Memory
741057		Mihailo	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	25 ms	39420 KiB

kangaroo

#include <bits/stdc++.h>
#define MOD 1000000007
using namespace std;

long long N, cs, cf, dp[2500][2500];

int main() {
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    cin>>N>>cs>>cf;
    dp[0][0]=1;
    for(int i=1; i<=N; i++) {
        for(int j=1; j<=N; j++) {
            if(i==cs||i==cf) {
                dp[i][j]=dp[i-1][j]+dp[i-1][j-1];
            }
            else dp[i][j]=max((j-(i>cs)-(i>cf)), 0)*dp[i-1][j-1]+j*dp[i-1][j+1];
            dp[i][j]%=MOD;
        }
    }
    cout<<dp[N][1];
    return 0;
}

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