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Submission #446886

# Submission time Handle Problem Language Result Execution time Memory
446886 2021-07-23T17:00:09 Z aniervs Kangaroo (CEOI16_kangaroo) C++17
100 / 100
 29 ms 22980 KB 
#ifdef LOCAL
#include <prettyprint.hpp>
#endif
#include<bits/stdc++.h>
#define endl '\n'
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define lg2(x) __lg(x)
#define rem_dupl(x) sort(all(x)); x.erase(unique(all(x)), x.end())
using namespace std;

typedef long long ll;
typedef double db;
typedef pair<int,int> ii;
#define x first
#define y second

//mt19937 rand32(chrono::steady_clock::now().time_since_epoch().count());
//mt19937_64 rand64(chrono::steady_clock::now().time_since_epoch().count());

const db eps = 1e-9;
const int maxn = (int)2e3 + 5;
const ll mod = (int)1e9 + 7; // 998244353

ll mul(ll a, ll b){
    return a * b % mod;
}
ll add(ll a, ll b){
    return (a + b)%mod;
}

ll dp[maxn][maxn];

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    cout.setf(ios::fixed); cout.precision(0);

    int n, s, t;
    cin >> n >> s >> t;
    dp[1][1] = 1;
    
    for(int i = 1; i < n; i++)
        for(int j = 1; j <= i; j++){
            if(i + 1 == s or i + 1 == t){
                dp[i+1][j] = add(dp[i + 1][j], dp[i][j]);
                dp[i+1][j+1] = add(dp[i + 1][j + 1], dp[i][j]);
                continue;
            }
            
            dp[i+1][j-1] = add(dp[i+1][j-1], mul(dp[i][j], j-1));
            dp[i+1][j+1] = add(dp[i+1][j+1], mul(dp[i][j], j + 1 - (int)(i >= s) - (int)(i >= t)));
        }
    
    cout << dp[n][1];
    
    return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 332 KB Output is correct
2 Correct 0 ms 332 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 332 KB Output is correct
2 Correct 0 ms 332 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 460 KB Output is correct
8 Correct 1 ms 452 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 1 ms 460 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 332 KB Output is correct
2 Correct 0 ms 332 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 460 KB Output is correct
8 Correct 1 ms 452 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 1 ms 460 KB Output is correct
12 Correct 1 ms 1228 KB Output is correct
13 Correct 1 ms 1100 KB Output is correct
14 Correct 1 ms 1228 KB Output is correct
15 Correct 1 ms 1228 KB Output is correct
16 Correct 1 ms 1228 KB Output is correct
17 Correct 1 ms 1228 KB Output is correct
18 Correct 1 ms 1100 KB Output is correct
19 Correct 1 ms 1228 KB Output is correct
20 Correct 1 ms 1228 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 332 KB Output is correct
2 Correct 0 ms 332 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 460 KB Output is correct
8 Correct 1 ms 452 KB Output is correct
9 Correct 1 ms 460 KB Output is correct
10 Correct 1 ms 460 KB Output is correct
11 Correct 1 ms 460 KB Output is correct
12 Correct 1 ms 1228 KB Output is correct
13 Correct 1 ms 1100 KB Output is correct
14 Correct 1 ms 1228 KB Output is correct
15 Correct 1 ms 1228 KB Output is correct
16 Correct 1 ms 1228 KB Output is correct
17 Correct 1 ms 1228 KB Output is correct
18 Correct 1 ms 1100 KB Output is correct
19 Correct 1 ms 1228 KB Output is correct
20 Correct 1 ms 1228 KB Output is correct
21 Correct 5 ms 4556 KB Output is correct
22 Correct 5 ms 5068 KB Output is correct
23 Correct 6 ms 5580 KB Output is correct
24 Correct 29 ms 22980 KB Output is correct
25 Correct 28 ms 22964 KB Output is correct
26 Correct 28 ms 22924 KB Output is correct
27 Correct 28 ms 22916 KB Output is correct
28 Correct 17 ms 15120 KB Output is correct