Submission #1367696

#	Time	Username	Problem	Language	Result	Execution time	Memory
1367696		po_rag526	캥거루 (CEOI16_kangaroo)	C++20	100 / 100	8 ms	464 KiB

kangaroo

#include <bits/stdc++.h>
using namespace std;
#define int long long

const int mod = 1000000007;

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, cs, cf;
    cin >> n >> cs >> cf;
    vector<int> dp(n + 5), ndp(n + 5);
    dp[0] = 1;
    for(int i = 1; i <= n; i++){
        fill(ndp.begin(), ndp.end(), 0);
        for(int j = 1; j <= n; j++){
            if(i == cs || i == cf){
                ndp[j] = (dp[j] + dp[j - 1])%mod;
            }else{
                ndp[j] = (ndp[j] + dp[j + 1] * j)%mod;
                int c = j;
                if(i > cs) c--;
                if(i > cf) c--;
                if(c > 0){
                    ndp[j] = (ndp[j] + dp[j - 1] * c)%mod;
                }
            }
        }
        dp = ndp;
    }
    cout << dp[1] % mod << '\n';
}

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