Submission #237838

#	Time	Username	Problem	Language	Result	Execution time	Memory
237838		thecodingwizard	Kangaroo (CEOI16_kangaroo)	C++11	100 / 100	29 ms	31616 KiB

kangaroo

#include <bits/stdc++.h>

using namespace std;

long long dp[2001][2001]; 

int main() {
    int n, cs, cf; cin >> n >> cs >> cf;

    for (int i = 0; i <= n;i++) for (int j = 0; j <= n; j++) dp[i][j] = 0;
    dp[1][1] = 1;
    for (int i = 2; i <= n; i++) {
        for (int j = 1; j <= i; j++) {
            if (i == cs || i == cf) {
                dp[i][j] = (dp[i-1][j-1] + dp[i-1][j])%1000000007;
            } else {
                dp[i][j] = ((dp[i-1][j+1]*j) + dp[i-1][j-1]*(j-(i>cs)-(i>cf))) % 1000000007;
            }
        }
    }
    cout << dp[n][1] << endl;

    return 0;
}

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