Submission #1118089

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118089		vjudge1	Kangaroo (CEOI16_kangaroo)	C++17	51 / 100	18 ms	15952 KiB

kangaroo

#pragma GCC optimize("O3")// ceoi 2016 day 1 p2//03:11 11-25-2024
#include<bits/stdc++.h>
#define ll unsigned long long
#define endl "\n"
#define AI ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
ll dp[1001][1001];
int main()
{
    AI
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    ll n,cs,cf,fixe=0,i,j,mod=1e9+7;
    cin>>n;
    cin>>cs>>cf;
    dp[1][1]=1;
    for(i=0;i<=100;i++)
    {
        for(j=0;j<=1000;j++)
        dp[i][j]=0;
    }
    dp[1][1]=1;
    for(i=1;i<=n;i++)
    {
        if(i==cs or i==cf)
        fixe++;
        for(j=1;j<i;j++)
        {
            if(i==cs or i==cf)
            {
                dp[i][j+1]+=dp[i-1][j];
                dp[i][j+1]%=mod;
                dp[i][j]+=dp[i-1][j];
                dp[i][j]%=mod;
            }
            else
            {
                dp[i][j+1]+=(dp[i-1][j]*(j-fixe+1))%mod;
                dp[i][j-1]+=(dp[i-1][j]*(j-1))%mod;
                dp[i][j+1]%=mod;
                dp[i][j-1]%=mod;
            }

        }
    }
    cout<<dp[n][1]%mod;

}
/*
Thanks to Rashad Mammadov
*/

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