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Submission #30839

# Submission time Handle Problem Language Result Execution time Memory
30839 2017-07-27T14:55:49 Z szawinis Kangaroo (CEOI16_kangaroo) C++14
100 / 100
 43 ms 17820 KB 
#include <bits/stdc++.h>
using namespace std;
const long long MOD = (1e9)+7;

inline void add(int& a, int b) { a = (a + b) % MOD; }
inline int mul(int a, int b) { return 1ll * a * b % MOD; }

int n, s, e, dp[2001][2001];
int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> n >> s >> e;
	dp[0][0] = 1;
	for(int i = 0; i < n-1; i++) for(int j = 0; j <= i; j++) {
		if(i+1 == s || i+1 == e) { // automatically decrease j by 1, since s, e not counted
			add(dp[i+1][j], dp[i][j]); // new cc
			if(j) add(dp[i+1][j-1], mul(dp[i][j], j)); // append to start/end of some cc
		} else {
			add(dp[i+1][j+1], dp[i][j]); // new cc
			if(j >= 2) add(dp[i+1][j-1], mul(dp[i][j], j*(j-1))); // join two non-empty cc
			if(i+1 > s && j) add(dp[i+1][j-1], mul(dp[i][j], j)); // append to start's cc
			if(i+1 > e && j) add(dp[i+1][j-1], mul(dp[i][j], j)); // append to end's cc
		}
	}
	cout << dp[n-1][0];
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 17820 KB Output is correct
2 Correct 0 ms 17820 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 17820 KB Output is correct
2 Correct 0 ms 17820 KB Output is correct
3 Correct 0 ms 17820 KB Output is correct
4 Correct 0 ms 17820 KB Output is correct
5 Correct 0 ms 17820 KB Output is correct
6 Correct 0 ms 17820 KB Output is correct
7 Correct 0 ms 17820 KB Output is correct
8 Correct 0 ms 17820 KB Output is correct
9 Correct 0 ms 17820 KB Output is correct
10 Correct 0 ms 17820 KB Output is correct
11 Correct 0 ms 17820 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 17820 KB Output is correct
2 Correct 0 ms 17820 KB Output is correct
3 Correct 0 ms 17820 KB Output is correct
4 Correct 0 ms 17820 KB Output is correct
5 Correct 0 ms 17820 KB Output is correct
6 Correct 0 ms 17820 KB Output is correct
7 Correct 0 ms 17820 KB Output is correct
8 Correct 0 ms 17820 KB Output is correct
9 Correct 0 ms 17820 KB Output is correct
10 Correct 0 ms 17820 KB Output is correct
11 Correct 0 ms 17820 KB Output is correct
12 Correct 0 ms 17820 KB Output is correct
13 Correct 0 ms 17820 KB Output is correct
14 Correct 0 ms 17820 KB Output is correct
15 Correct 0 ms 17820 KB Output is correct
16 Correct 0 ms 17820 KB Output is correct
17 Correct 0 ms 17820 KB Output is correct
18 Correct 0 ms 17820 KB Output is correct
19 Correct 0 ms 17820 KB Output is correct
20 Correct 0 ms 17820 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 17820 KB Output is correct
2 Correct 0 ms 17820 KB Output is correct
3 Correct 0 ms 17820 KB Output is correct
4 Correct 0 ms 17820 KB Output is correct
5 Correct 0 ms 17820 KB Output is correct
6 Correct 0 ms 17820 KB Output is correct
7 Correct 0 ms 17820 KB Output is correct
8 Correct 0 ms 17820 KB Output is correct
9 Correct 0 ms 17820 KB Output is correct
10 Correct 0 ms 17820 KB Output is correct
11 Correct 0 ms 17820 KB Output is correct
12 Correct 0 ms 17820 KB Output is correct
13 Correct 0 ms 17820 KB Output is correct
14 Correct 0 ms 17820 KB Output is correct
15 Correct 0 ms 17820 KB Output is correct
16 Correct 0 ms 17820 KB Output is correct
17 Correct 0 ms 17820 KB Output is correct
18 Correct 0 ms 17820 KB Output is correct
19 Correct 0 ms 17820 KB Output is correct
20 Correct 0 ms 17820 KB Output is correct
21 Correct 3 ms 17820 KB Output is correct
22 Correct 6 ms 17820 KB Output is correct
23 Correct 6 ms 17820 KB Output is correct
24 Correct 33 ms 17820 KB Output is correct
25 Correct 26 ms 17820 KB Output is correct
26 Correct 29 ms 17820 KB Output is correct
27 Correct 43 ms 17820 KB Output is correct
28 Correct 26 ms 17820 KB Output is correct