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Submission #442690

# Submission time Handle Problem Language Result Execution time Memory
442690 2021-07-08T15:24:54 Z pal550 Kangaroo (CEOI16_kangaroo) C++17
100 / 100
 45 ms 31608 KB 
#include<bits/stdc++.h>
#define mod 1000000007
using namespace std;

typedef long long ll;

int n, a, b;
inline int add(int a, int b)
{
    if(!b)
        return a;
    int x = a+b;
    if(x >= mod)
        x -= mod;
    else
        if(x < 0)
            x += mod;
    return x;
}
ll mul(ll a, ll b)
{
    return (a * b) % mod;
}
ll dp[2002][2002];
int main()
{
    cin >> n >> a >> b;
    dp[1][1] = 1;
    for(int i = 2; i <= n; ++i)
        for(int j = 1; j <= n; ++j)
        {
            if(i == a || i == b)
                dp[i][j] = add(dp[i-1][j-1], dp[i-1][j]);
            else
                dp[i][j] = add(mul(dp[i-1][j+1], j), mul(dp[i-1][j-1], j - (i > a) - (i > b)));
        }
    cout << dp[n][1];
    return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 ms 460 KB Output is correct
6 Correct 1 ms 460 KB Output is correct
7 Correct 1 ms 332 KB Output is correct
8 Correct 0 ms 460 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 0 ms 460 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 ms 460 KB Output is correct
6 Correct 1 ms 460 KB Output is correct
7 Correct 1 ms 332 KB Output is correct
8 Correct 0 ms 460 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 0 ms 460 KB Output is correct
12 Correct 1 ms 1356 KB Output is correct
13 Correct 1 ms 1228 KB Output is correct
14 Correct 1 ms 1356 KB Output is correct
15 Correct 1 ms 1356 KB Output is correct
16 Correct 1 ms 1356 KB Output is correct
17 Correct 1 ms 1356 KB Output is correct
18 Correct 1 ms 1228 KB Output is correct
19 Correct 1 ms 1356 KB Output is correct
20 Correct 1 ms 1356 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 1 ms 460 KB Output is correct
5 Correct 1 ms 460 KB Output is correct
6 Correct 1 ms 460 KB Output is correct
7 Correct 1 ms 332 KB Output is correct
8 Correct 0 ms 460 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 0 ms 460 KB Output is correct
12 Correct 1 ms 1356 KB Output is correct
13 Correct 1 ms 1228 KB Output is correct
14 Correct 1 ms 1356 KB Output is correct
15 Correct 1 ms 1356 KB Output is correct
16 Correct 1 ms 1356 KB Output is correct
17 Correct 1 ms 1356 KB Output is correct
18 Correct 1 ms 1228 KB Output is correct
19 Correct 1 ms 1356 KB Output is correct
20 Correct 1 ms 1356 KB Output is correct
21 Correct 6 ms 6220 KB Output is correct
22 Correct 9 ms 6868 KB Output is correct
23 Correct 8 ms 7756 KB Output is correct
24 Correct 45 ms 31592 KB Output is correct
25 Correct 40 ms 31556 KB Output is correct
26 Correct 45 ms 31608 KB Output is correct
27 Correct 41 ms 31428 KB Output is correct
28 Correct 26 ms 23732 KB Output is correct