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Submission #23732

# Submission time Handle Problem Language Result Execution time Memory
23732 2017-05-24T10:39:43 Z gs14004 Kangaroo (CEOI16_kangaroo) C++11
100 / 100
 19 ms 33424 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long lint;
typedef pair<int, int> pi;
const int mod = 1e9 + 7;

lint dp[2005][2005];
int n, s, t;

int main(){
	cin >> n >> s >> t;
	dp[n+1][1] = 1;
	int f = 2;
	for(int i=n; i; i--){
		for(int j=1; j<=n; j++){
			if(i == s || i == t){
				dp[i][j] = (dp[i+1][j] + dp[i+1][j+1]) % mod;
			}
			else{
				dp[i][j] = (dp[i+1][j-1] * (j-1) + dp[i+1][j+1] * (j + 1 - f)) % mod;
			}
		}
		if(i == s || i == t) f--;
	}
	cout << dp[2][1];
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 33424 KB Output is correct
2 Correct 0 ms 33424 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 33424 KB Output is correct
2 Correct 0 ms 33424 KB Output is correct
3 Correct 0 ms 33424 KB Output is correct
4 Correct 0 ms 33424 KB Output is correct
5 Correct 0 ms 33424 KB Output is correct
6 Correct 0 ms 33424 KB Output is correct
7 Correct 0 ms 33424 KB Output is correct
8 Correct 0 ms 33424 KB Output is correct
9 Correct 0 ms 33424 KB Output is correct
10 Correct 0 ms 33424 KB Output is correct
11 Correct 0 ms 33424 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 33424 KB Output is correct
2 Correct 0 ms 33424 KB Output is correct
3 Correct 0 ms 33424 KB Output is correct
4 Correct 0 ms 33424 KB Output is correct
5 Correct 0 ms 33424 KB Output is correct
6 Correct 0 ms 33424 KB Output is correct
7 Correct 0 ms 33424 KB Output is correct
8 Correct 0 ms 33424 KB Output is correct
9 Correct 0 ms 33424 KB Output is correct
10 Correct 0 ms 33424 KB Output is correct
11 Correct 0 ms 33424 KB Output is correct
12 Correct 0 ms 33424 KB Output is correct
13 Correct 0 ms 33424 KB Output is correct
14 Correct 0 ms 33424 KB Output is correct
15 Correct 0 ms 33424 KB Output is correct
16 Correct 0 ms 33424 KB Output is correct
17 Correct 0 ms 33424 KB Output is correct
18 Correct 0 ms 33424 KB Output is correct
19 Correct 0 ms 33424 KB Output is correct
20 Correct 0 ms 33424 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 33424 KB Output is correct
2 Correct 0 ms 33424 KB Output is correct
3 Correct 0 ms 33424 KB Output is correct
4 Correct 0 ms 33424 KB Output is correct
5 Correct 0 ms 33424 KB Output is correct
6 Correct 0 ms 33424 KB Output is correct
7 Correct 0 ms 33424 KB Output is correct
8 Correct 0 ms 33424 KB Output is correct
9 Correct 0 ms 33424 KB Output is correct
10 Correct 0 ms 33424 KB Output is correct
11 Correct 0 ms 33424 KB Output is correct
12 Correct 0 ms 33424 KB Output is correct
13 Correct 0 ms 33424 KB Output is correct
14 Correct 0 ms 33424 KB Output is correct
15 Correct 0 ms 33424 KB Output is correct
16 Correct 0 ms 33424 KB Output is correct
17 Correct 0 ms 33424 KB Output is correct
18 Correct 0 ms 33424 KB Output is correct
19 Correct 0 ms 33424 KB Output is correct
20 Correct 0 ms 33424 KB Output is correct
21 Correct 0 ms 33424 KB Output is correct
22 Correct 0 ms 33424 KB Output is correct
23 Correct 0 ms 33424 KB Output is correct
24 Correct 13 ms 33424 KB Output is correct
25 Correct 16 ms 33424 KB Output is correct
26 Correct 13 ms 33424 KB Output is correct
27 Correct 19 ms 33424 KB Output is correct
28 Correct 13 ms 33424 KB Output is correct