제출 #1139241

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1139241		THXuan	Kangaroo (CEOI16_kangaroo)	C++20	100 / 100	18 ms	31816 KiB

kangaroo

// dp[i][j] = the number of ways if consider the first i-th element and divide it into j
#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#define INF 1e9
typedef long long ll;
using namespace std;

const ll MOD = 1e9 + 7;

ll dp[2005][2005];

void solve()
{
    int n, s, e; cin >> n >> s >> e;
    dp[1][1] = 1;
    for (int i = 2; i <= n; i++) {
        if (i != s && i != e) {
            for (int j = 1; j <= n; j++) dp[i][j] = (dp[i - 1][j + 1] * j + dp[i - 1][j - 1] * (j - (i > s) - (i > e))) % MOD;
        }
        else {
            for (int j = 1; j <= n; j++) {
                dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % MOD;
            }
        }
    }
    cout << dp[n][1] % MOD << "\n";
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;// cin >> t;
    while (t--) solve();
    return 0;
}

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