Submission #604898

#	Time	Username	Problem	Language	Result	Execution time	Memory
604898		Vanilla	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	44 ms	22960 KiB

kangaroo

#include <bits/stdc++.h>
using namespace std;typedef long long p;p m=1e9+7;p d[2001][2001];int main(){int n,a,b;cin>>n>>a>>b;d[0][0]=1;for(p i=1;i<=n;i++){for(p j=1;j<=i;j++){if(i==a||i==b)d[i][j]=(d[i-1][j-1]+d[i-1][j])%m;else d[i][j]=(d[i-1][j+1]*j%m+d[i-1][j-1]*(j-(i>a)-(i>b))%m)%m;}}cout<<d[n][1];return 0;}

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