oj.uz

Submission #850021

# Submission time Handle Problem Language Result Execution time Memory
850021 2023-09-15T16:00:21 Z fanwen Kangaroo (CEOI16_kangaroo) C++17
100 / 100
 18 ms 16216 KB 
#include <bits/stdc++.h>

using namespace std;

#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
#define REP(i, n) for (int i = 0, _n = n; i < _n; ++i)
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define FORE(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define debug(...) "[" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }

template <class A, class B> bool minimize(A &a, B b)  { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b)  { if (a < b) { a = b; return true; } return false; }

template <int Mod> 
struct Modular {
private :
    int val;
    static int inverse(int a, int b) {
        a %= b;
        assert(a);
        if(a == 1) return 1;
        return int(b - (long long) inverse(b, a) * (long long) b / a);
    }
public :
    Modular(long long x = 0) : 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; }

    Modular& operator = (const long long &x) { val = x % Mod; if(val < 0) val += Mod; return *this; }
    Modular& operator = (const Modular &x) { val = x.val; return *this; }

    friend istream & operator >> (istream &in, Modular &a) { long long x; in >> x; a = Modular(x); return in; }
    friend ostream & operator << (ostream &out, const Modular &a) { return out << a.val; }

    explicit operator int() const { return val; }
    explicit operator bool() const { return val > 0; }

    Modular inv() const {
        Modular res;
        res.val = inverse(val, Mod);
        return res;
    }

    Modular operator ++() { (*this) += 1; return *this; }
    Modular operator --() { (*this) -= 1; return *this; }
    Modular operator ++(int) { (*this) += 1; return *this - 1; }
    Modular operator --(int) { (*this) -= 1; return *this + 1; }

    Modular operator + () const { return *this; }
    Modular operator - () const {
        Modular res;
        res.val = (val ? Mod - val : 0);
        return res;
    }

    Modular& operator += (const Modular &a) {
        val += a.val;
        if(val >= Mod) 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 = 1LL * val * a.val % Mod;
        return *this;
    }
    Modular& operator /= (const Modular &a) {
        (*this) *= a.inv();
        return *this;
    }
    friend Modular operator + (const Modular &a, const Modular &b) { return Modular(a) += b; }
    friend Modular operator - (const Modular &a, const Modular &b) { return Modular(a) -= b; }
    friend Modular operator * (const Modular &a, const Modular &b) { return Modular(a) *= b; }
    friend Modular operator / (const Modular &a, const Modular &b) { return Modular(a) /= b; }
};

// const int Mod = 998244353;
// const int Mod = 1e9 + 9; // 1000000009 
const int Mod = 1e9 + 7; // 1000000007

using Modint = Modular <Mod>;

template <class T> T pow(T a, long long b) {
    T ans = 1, mul = a;
    for (; b; b >>= 1) {
        if(b & 1LL) ans *= mul;
        mul *= mul;
    }
    return ans;
}

Modint dp[2005][2005];

void you_make_it(void) {
    int n, cs, cf; cin >> n >> cs >> cf;
    dp[0][0] = 1;
    FOR(i, 1, n) {
    	FOR(j, 1, n) {
    		if(i == cs || i == cf) {
    			dp[i][j] = dp[i - 1][j] + dp[i - 1][j - 1];
    		} else {
    			dp[i][j] = dp[i - 1][j + 1] * j + dp[i - 1][j - 1] * (j - (i > cs) - (i > cf));
    		}
    	}
    }
    cout << dp[n][1];
}

signed main() {

#ifdef LOCAL
    freopen("TASK.inp", "r", stdin);
    freopen("TASK.out", "w", stdout);
#endif
    auto start_time = chrono::steady_clock::now();

    cin.tie(0), cout.tie(0) -> sync_with_stdio(0);

    you_make_it();

    auto end_time = chrono::steady_clock::now();

    cerr << "\nExecution time : " << chrono::duration_cast <chrono::milliseconds> (end_time - start_time).count() << "[ms]" << endl;

    return (0 ^ 0);
}

// Dream it. Wish it. Do it.

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 15960 KB Output is correct
2 Correct 3 ms 15964 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 15960 KB Output is correct
2 Correct 3 ms 15964 KB Output is correct
3 Correct 4 ms 16216 KB Output is correct
4 Correct 3 ms 15964 KB Output is correct
5 Correct 3 ms 15960 KB Output is correct
6 Correct 3 ms 15960 KB Output is correct
7 Correct 3 ms 15960 KB Output is correct
8 Correct 3 ms 15960 KB Output is correct
9 Correct 3 ms 15960 KB Output is correct
10 Correct 3 ms 15960 KB Output is correct
11 Correct 3 ms 15960 KB Output is correct

Subtask #3
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 15960 KB Output is correct
2 Correct 3 ms 15964 KB Output is correct
3 Correct 4 ms 16216 KB Output is correct
4 Correct 3 ms 15964 KB Output is correct
5 Correct 3 ms 15960 KB Output is correct
6 Correct 3 ms 15960 KB Output is correct
7 Correct 3 ms 15960 KB Output is correct
8 Correct 3 ms 15960 KB Output is correct
9 Correct 3 ms 15960 KB Output is correct
10 Correct 3 ms 15960 KB Output is correct
11 Correct 3 ms 15960 KB Output is correct
12 Correct 3 ms 15960 KB Output is correct
13 Correct 3 ms 15960 KB Output is correct
14 Correct 3 ms 15960 KB Output is correct
15 Correct 3 ms 15960 KB Output is correct
16 Correct 3 ms 15960 KB Output is correct
17 Correct 3 ms 15960 KB Output is correct
18 Correct 3 ms 15960 KB Output is correct
19 Correct 4 ms 16116 KB Output is correct
20 Correct 3 ms 15964 KB Output is correct

Subtask #4
49.0 / 49.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 15960 KB Output is correct
2 Correct 3 ms 15964 KB Output is correct
3 Correct 4 ms 16216 KB Output is correct
4 Correct 3 ms 15964 KB Output is correct
5 Correct 3 ms 15960 KB Output is correct
6 Correct 3 ms 15960 KB Output is correct
7 Correct 3 ms 15960 KB Output is correct
8 Correct 3 ms 15960 KB Output is correct
9 Correct 3 ms 15960 KB Output is correct
10 Correct 3 ms 15960 KB Output is correct
11 Correct 3 ms 15960 KB Output is correct
12 Correct 3 ms 15960 KB Output is correct
13 Correct 3 ms 15960 KB Output is correct
14 Correct 3 ms 15960 KB Output is correct
15 Correct 3 ms 15960 KB Output is correct
16 Correct 3 ms 15960 KB Output is correct
17 Correct 3 ms 15960 KB Output is correct
18 Correct 3 ms 15960 KB Output is correct
19 Correct 4 ms 16116 KB Output is correct
20 Correct 3 ms 15964 KB Output is correct
21 Correct 4 ms 15960 KB Output is correct
22 Correct 5 ms 15960 KB Output is correct
23 Correct 6 ms 15960 KB Output is correct
24 Correct 18 ms 15964 KB Output is correct
25 Correct 18 ms 15960 KB Output is correct
26 Correct 18 ms 15960 KB Output is correct
27 Correct 18 ms 15960 KB Output is correct
28 Correct 12 ms 15960 KB Output is correct