Submission #960643

#	Time	Username	Problem	Language	Result	Execution time	Memory
960643		teo_thrash	Kangaroo (CEOI16_kangaroo)	C++14	6 / 100	1 ms	2396 KiB

kangaroo

// it is your desire to work hard

#include<bits/stdc++.h>
#define pb push_back

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

const int maxn=2e3+3;
const int mod=1e9+7;

int n;
int dp[maxn][maxn];
int cs, cf;

int main(){

ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);

cin>>n;
cin>>cs>>cf;

dp[1][1]=1;

for(int i=2; i<=n; i++){
    for(int j=1; j<=n; j++){
        int rem=0;
        if(i>cs) rem++;
        if(i>cf) rem++;

        if(i==cs or i==cf){
            dp[i][j] = (dp[i-1][j-1])%mod + (dp[i-1][j])%mod;
        }else{
            dp[i][j] = (dp[i-1][j+1]*j)%mod + (dp[i-1][j-1]*(j-rem))%mod;
        }
        dp[i][j]%=mod;
    }
}
cout<<dp[n][1]<<endl;

return 0;
}

• Subtask 1: 6 / 6
• Subtask 2: 0 / 30
• Subtask 3: 0 / 15
• Subtask 4: 0 / 49