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Submission #65728

# Submission time Handle Problem Language Result Execution time Memory
65728 2018-08-08T14:11:39 Z Namnamseo Kangaroo (CEOI16_kangaroo) C++17
100 / 100
 66 ms 23476 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

ll n, s, f;

ll ans;
const ll mod = int(1e9) + 7;

ll dp[2010][2010];

int main()
{
	cin >> n >> s >> f;
	dp[0][0] = 1;
	for(ll i=1; i<n; ++i){
		if(i == s || i == f){
			for(int j=0; j<i; ++j)
				(dp[i][j] += dp[i-1][j]) %= mod;
			for(int j=1; j<i; ++j)
				(dp[i][j-1] += dp[i-1][j] * j % mod) %= mod;
			continue;
		}
		for(ll j=0; j<i; ++j){
			if(j >= 2){
				(dp[i][j-1] += dp[i-1][j] * j % mod * (j-1) % mod) %= mod;
			}
			if(i >= s){
				(dp[i][j-1] += dp[i-1][j] * j % mod) %= mod;
			}
			if(i >= f){
				(dp[i][j-1] += dp[i-1][j] * j % mod) %= mod;
			}
			(dp[i][j+1] += dp[i-1][j]) %= mod;
		}
	}
	cout << dp[n-1][0] << endl;
	return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 380 KB Output is correct
2 Correct 2 ms 380 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 380 KB Output is correct
2 Correct 2 ms 380 KB Output is correct
3 Correct 2 ms 564 KB Output is correct
4 Correct 2 ms 788 KB Output is correct
5 Correct 2 ms 788 KB Output is correct
6 Correct 2 ms 788 KB Output is correct
7 Correct 3 ms 788 KB Output is correct
8 Correct 3 ms 800 KB Output is correct
9 Correct 2 ms 804 KB Output is correct
10 Correct 2 ms 808 KB Output is correct
11 Correct 2 ms 812 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 380 KB Output is correct
2 Correct 2 ms 380 KB Output is correct
3 Correct 2 ms 564 KB Output is correct
4 Correct 2 ms 788 KB Output is correct
5 Correct 2 ms 788 KB Output is correct
6 Correct 2 ms 788 KB Output is correct
7 Correct 3 ms 788 KB Output is correct
8 Correct 3 ms 800 KB Output is correct
9 Correct 2 ms 804 KB Output is correct
10 Correct 2 ms 808 KB Output is correct
11 Correct 2 ms 812 KB Output is correct
12 Correct 3 ms 1584 KB Output is correct
13 Correct 3 ms 1588 KB Output is correct
14 Correct 3 ms 1596 KB Output is correct
15 Correct 3 ms 1604 KB Output is correct
16 Correct 4 ms 1604 KB Output is correct
17 Correct 5 ms 1604 KB Output is correct
18 Correct 3 ms 1604 KB Output is correct
19 Correct 5 ms 1616 KB Output is correct
20 Correct 4 ms 1700 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 380 KB Output is correct
2 Correct 2 ms 380 KB Output is correct
3 Correct 2 ms 564 KB Output is correct
4 Correct 2 ms 788 KB Output is correct
5 Correct 2 ms 788 KB Output is correct
6 Correct 2 ms 788 KB Output is correct
7 Correct 3 ms 788 KB Output is correct
8 Correct 3 ms 800 KB Output is correct
9 Correct 2 ms 804 KB Output is correct
10 Correct 2 ms 808 KB Output is correct
11 Correct 2 ms 812 KB Output is correct
12 Correct 3 ms 1584 KB Output is correct
13 Correct 3 ms 1588 KB Output is correct
14 Correct 3 ms 1596 KB Output is correct
15 Correct 3 ms 1604 KB Output is correct
16 Correct 4 ms 1604 KB Output is correct
17 Correct 5 ms 1604 KB Output is correct
18 Correct 3 ms 1604 KB Output is correct
19 Correct 5 ms 1616 KB Output is correct
20 Correct 4 ms 1700 KB Output is correct
21 Correct 12 ms 5080 KB Output is correct
22 Correct 12 ms 5500 KB Output is correct
23 Correct 13 ms 6016 KB Output is correct
24 Correct 61 ms 23432 KB Output is correct
25 Correct 65 ms 23472 KB Output is correct
26 Correct 62 ms 23476 KB Output is correct
27 Correct 66 ms 23476 KB Output is correct
28 Correct 40 ms 23476 KB Output is correct