Submission #1114693

#	Time	Username	Problem	Language	Result	Execution time	Memory
1114693		koukirocks	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	33 ms	31828 KiB

kangaroo

#include <bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0); cin.tie(0)
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx,avx2")
//#pragma GCC target("popcnt")
 
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
 
const ll MAX=2e5+10,P=1e9+7;
const ll INF=0x3f3f3f3f,oo=0x3f3f3f3f3f3f3f3f;
const ldb eps=1e-6;
const ldb PI=acos(-1.0);
const int dir[4][2]={{0,1},{0,-1},{1,0},{-1,0}};
template<typename T>
using vvector = vector<vector<T>>;

int main() {
    speed;
    ll n,s,t;
    cin>>n>>s>>t;
    vvector<ll> dp(n+1,vector<ll>(n+1));
    dp[1][1]=1;
    for (int i=2;i<=n;i++) {
        for (int j=1;j<=i;j++) {
            if (i==s or i==t) dp[i][j]=dp[i-1][j-1]+dp[i-1][j];
            else {
                dp[i][j]=(j-(i>s)-(i>t))*dp[i-1][j-1]%P+j*dp[i-1][j+1]%P;
            }
            dp[i][j]%=P;
        }
    }
    cout<<dp[n][1]<<"\n";
    return 0;
}

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