Submission #1118212

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118212		vjudge1	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	41 ms	31772 KiB

kangaroo

#pragma GCC optimize("O3")
#include<bits/stdc++.h>
#define ll long long
#define endl "\n"
#define AI ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
ll dp[2001][2001];
int main()
{
    AI
    //freopen("kangaroo.in", "r", stdin);
   // freopen("kangaroo.out", "w", stdout);
    ll n,cs,cf,i,j,f=0,mod=1e9+7;
    cin>>n>>cs>>cf;
    dp[0][0]=1;
    for(i=1;i<=n;i++)
    {
        if(i==cf or i==cs)
        f++;
        for(j=1;j<=n;j++)
        {
            if(i==cf or i==cs)
            {
                dp[i][j]+=dp[i-1][j];
                dp[i][j]%=mod;
                dp[i][j]+=dp[i-1][j-1];
                dp[i][j]%=mod;
            }
            else
            {
                dp[i][j]+=dp[i-1][j-1]*(j-f);
                dp[i][j]%=mod;
                dp[i][j]+=dp[i-1][j+1]*j;
                dp[i][j]%=mod;
            }
        }
    }
    cout<<dp[n][1];

}

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