Submission #545539

#	Time	Username	Problem	Language	Result	Execution time	Memory
545539		sidon	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	9 ms	336 KiB

kangaroo

#include <bits/stdc++.h>
using namespace std;
#define int int64_t

int N, cs, cf, dp[2002] {1}, prv[2002];

int32_t main() {
	cin >> N >> cs >> cf;

	for(int i = 1; i <= N; ++i) {
		copy(dp, dp + 2002, prv);
		dp[0] = 0;
		for(int j = 1; j <= N; ++j)
			dp[j] = (i == cs || i == cf ? (prv[j-1] + prv[j]) : prv[j+1] * j + prv[j-1] * (j - (i > cs) - (i > cf))) % int(1e9+7);
	}

	cout << dp[1];
}

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