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Submission #699115

# Submission time Handle Problem Language Result Execution time Memory
699115 2023-02-15T16:08:29 Z mate Kangaroo (CEOI16_kangaroo) C++14
100 / 100
 23 ms 16084 KB 
#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define ff first
#define ss second
#define pb push_back

using namespace std;

template <int MOD>
class Modular {
private:
    int val;
    static const int mod = MOD;
    Modular inverse (const Modular &A) {
        Modular u = 0, v = 1;
        int a = A.val;
        int b = mod;
        while(a != 0) {
            int t = b / a;
            b -= t * a; swap(b, a);
            u -= t * v; swap(u, v);
        }
        return (b == 1) ? u : 0;
    }
public:
    explicit operator int() const {
        return val;
    }
    Modular() { val = 0; }
    Modular(ll x) {
        val = x % mod;
        if(val < 0) val += mod;
    }
    friend bool operator==(const Modular &A, const Modular &B) { return A.val == B.val; }
    friend bool operator!=(const Modular &A, const Modular &B) { return A.val != B.val; }
    friend bool operator<(const Modular &A, const Modular &B) { return A.val < B.val; }
    friend bool operator>(const Modular &A, const Modular &B) { return A.val > B.val; }
    Modular &operator+=(const Modular &A) { val += A.val; val %= mod; return *this; }
    Modular &operator-=(const Modular &A) { val -= A.val; if(val < 0) val += mod; return *this; }
    Modular &operator*=(const Modular &A) { val = (int)((ll)val * A.val % mod); return *this; }
    Modular &operator/=(const Modular &A) { return *this *= inverse(A); }
    Modular operator-() const { return Modular(-val); }
    Modular &operator++() { return *this += 1; }
    Modular &operator--() { return *this -= 1; }
    friend Modular operator+(Modular A, const Modular &B) { return A += B; }
    friend Modular operator-(Modular A, const Modular &B) { return A -= B; }
    friend Modular operator*(Modular A, const Modular &B) { return A *= B; }
    friend Modular operator/(Modular A, const Modular &B) { return A /= B; }
    friend istream& operator>>(istream& stream, Modular &A) { ll x; stream >> x; A = Modular(x); return stream; }
    friend ostream& operator<<(ostream& stream, Modular &A) { return stream << A.val; }
};

const int N = 2000;
const int mod = 1e9 + 7;
const int INF = 1e9 + 1;

using mint = Modular<mod>;

mint dp[N + 5][N + 5];

int main() {
    int n, s, e;
    cin >> n >> s >> e;
    dp[1][1] = 1;
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= i; j++) {
            if(i + 1 == s || i + 1 == e) {
                dp[i + 1][j + 1] += dp[i][j];
                dp[i + 1][j] += dp[i][j];
                continue;
            }
            int points;
            // Add as component
            points = j + 1;
            if(s <= i) points--;
            if(e <= i) points--;
            dp[i + 1][j + 1] += dp[i][j] * points;
            // Marge components
            points = j - 1;
            dp[i + 1][j - 1] += dp[i][j] * points;
        }
    }
    cout << dp[n][1] << " ";
//    vector<int> vec;
//    for(int i = 1; i <= n; i++) {
//        vec.pb(i);
//    }
//    int cnt = 0;
//    do {
//        bool isGood = true;
//        if(vec[0] != s || vec.back() != e) continue;
//        for(int i = 2; i < vec.size(); i++) {
//            if(vec[i - 2] < vec[i - 1] && vec[i - 1] < vec[i]) {
//                isGood = false;
//                break;
//            }
//            if(vec[i - 2] > vec[i - 1] && vec[i - 1] > vec[i]) {
//                isGood = false;
//                break;
//            }
//        }
//        if(isGood) cnt++;
//    }while(next_permutation(vec.begin(), vec.end()));
//    cout << cnt << " ";
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 15956 KB Output is correct
2 Correct 6 ms 15956 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 15956 KB Output is correct
2 Correct 6 ms 15956 KB Output is correct
3 Correct 6 ms 15956 KB Output is correct
4 Correct 6 ms 16032 KB Output is correct
5 Correct 7 ms 15984 KB Output is correct
6 Correct 6 ms 15956 KB Output is correct
7 Correct 7 ms 15956 KB Output is correct
8 Correct 8 ms 15956 KB Output is correct
9 Correct 6 ms 15992 KB Output is correct
10 Correct 6 ms 15956 KB Output is correct
11 Correct 7 ms 16004 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 15956 KB Output is correct
2 Correct 6 ms 15956 KB Output is correct
3 Correct 6 ms 15956 KB Output is correct
4 Correct 6 ms 16032 KB Output is correct
5 Correct 7 ms 15984 KB Output is correct
6 Correct 6 ms 15956 KB Output is correct
7 Correct 7 ms 15956 KB Output is correct
8 Correct 8 ms 15956 KB Output is correct
9 Correct 6 ms 15992 KB Output is correct
10 Correct 6 ms 15956 KB Output is correct
11 Correct 7 ms 16004 KB Output is correct
12 Correct 6 ms 15932 KB Output is correct
13 Correct 7 ms 16040 KB Output is correct
14 Correct 8 ms 15968 KB Output is correct
15 Correct 8 ms 15992 KB Output is correct
16 Correct 7 ms 16084 KB Output is correct
17 Correct 8 ms 16040 KB Output is correct
18 Correct 7 ms 15956 KB Output is correct
19 Correct 7 ms 16032 KB Output is correct
20 Correct 7 ms 15932 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 15956 KB Output is correct
2 Correct 6 ms 15956 KB Output is correct
3 Correct 6 ms 15956 KB Output is correct
4 Correct 6 ms 16032 KB Output is correct
5 Correct 7 ms 15984 KB Output is correct
6 Correct 6 ms 15956 KB Output is correct
7 Correct 7 ms 15956 KB Output is correct
8 Correct 8 ms 15956 KB Output is correct
9 Correct 6 ms 15992 KB Output is correct
10 Correct 6 ms 15956 KB Output is correct
11 Correct 7 ms 16004 KB Output is correct
12 Correct 6 ms 15932 KB Output is correct
13 Correct 7 ms 16040 KB Output is correct
14 Correct 8 ms 15968 KB Output is correct
15 Correct 8 ms 15992 KB Output is correct
16 Correct 7 ms 16084 KB Output is correct
17 Correct 8 ms 16040 KB Output is correct
18 Correct 7 ms 15956 KB Output is correct
19 Correct 7 ms 16032 KB Output is correct
20 Correct 7 ms 15932 KB Output is correct
21 Correct 8 ms 15964 KB Output is correct
22 Correct 8 ms 15956 KB Output is correct
23 Correct 9 ms 15956 KB Output is correct
24 Correct 23 ms 15932 KB Output is correct
25 Correct 21 ms 15956 KB Output is correct
26 Correct 21 ms 16020 KB Output is correct
27 Correct 20 ms 15956 KB Output is correct
28 Correct 14 ms 16036 KB Output is correct