Submission #740612

#	Time	Username	Problem	Language	Result	Execution time	Memory
740612		MladenP	Kangaroo (CEOI16_kangaroo)	C++17	0 / 100	0 ms	340 KiB

kangaroo

#include <iostream>
#define MAXN 2010
#define MOD 1000000007
using namespace std;
long long dp[MAXN][MAXN];
int main() {
    ios::sync_with_stdio(false); cin.tie(0);
    long long n, cs, cf;
    cin >> n >> cs >> cf; 
    dp[1][1] = 1;
    for (int i = 2; i <= n; i++) {
        for (long long j = 1; j <= i; j++) {
            if (i == cs || i == cf) {
                dp[i][j] = dp[i-1][j-1] + dp[i-1][j];
                if (dp[i][j] >= MOD) dp[i][j] %= MOD;
            } else {
                dp[i][j] = j * dp[i-1][j+1];
                dp[i][j] += (j+1 - (cs < i) - (cf < i)) * dp[i-1][j-1];
                if (dp[i][j] >= MOD) dp[i][j] %= MOD;
            }
        }
    }
    cout << dp[n][1];
    return 0;
}

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