Submission #330849

#	Time	Username	Problem	Language	Result	Execution time	Memory
330849		Falcon	Žarulje (COI15_zarulje)	C++17	60 / 100	120 ms	3876 KiB

zarulje

#pragma GCC optimize("O2")

#include <bits/stdc++.h>

#ifdef DEBUG
#include "debug.hpp"
#endif

using namespace std;

#define all(c)              (c).begin(), (c).end()
#define rall(c)             (c).rbegin(), (c).rend()
#define traverse(c, it)     for(auto it = (c).begin(); it != (c).end(); ++it)
#define rep(i, N)           for(int i = 0; i < (N); ++i)
#define rrep(i, N)          for(int i = (N) - 1; i >= 0; --i)
#define rep1(i, N)          for(int i = 1; i <= (N); ++i)
#define rep2(i, s, e)       for(int i = (s); i <= (e); ++i)
#define rep3(i, s, e, d)    for(int i = (s); (d) >= 0 ? i <= (e) : i >= (e); i += (d))

#ifdef DEBUG
#define debug(x...)         { \
                            ++dbg::depth; \
                            string dbg_vals = dbg::to_string(x); \
                            --dbg::depth; \
                            dbg::fprint(__func__, __LINE__, #x, dbg_vals); \
                            }

#define light_debug(x)      { \
                            dbg::light = true; \
                            dbg::dout << __func__ << ":" << __LINE__; \
                            dbg::dout << "  " << #x << " = " << x << endl; \
                            dbg::light = false; \
                            }
#else
#define debug(x...)         42
#define light_debug(x)      42
#endif


using ll = long long;

template<typename T>
inline T& ckmin(T& a, T b) { return a = a > b ? b : a; }

template<typename T>
inline T& ckmax(T& a, T b) { return a = a < b ? b : a; }


class Modular {
    int value;
    
public:
    static int mod;

    Modular(long long x = 0) {
        value = (int)((x % mod + mod) % mod);
    }

    inline Modular& operator +=(Modular x) {
        value += x.value;
        if(value >= mod) value -= mod;
        return *this;
    }

    inline Modular& operator -=(Modular x) {
        value -= x.value;
        if(value < 0) value += mod;
        return *this;
    }

    inline Modular& operator *=(Modular x) {
        value = int((long long)x.value * value % mod);
        return *this;
    }
    
    // TODO : Make this Extended Euclid to handle composite moduli.
    inline Modular& operator /=(Modular x) {
        return *this *= x.pow(-1);
    }

    inline Modular operator -() const {
        return Modular(-value);
    }

    inline Modular& operator ++() {
        return *this += 1;
    }

    inline Modular& operator --() {
        return *this -= 1;
    }

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

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

    Modular pow(long long n) const { 
        while(n < 0) n += mod - 1;
        Modular v(1), a(value);
        for(; n; a *= a, n >>= 1)
            if(n & 1) v *= a;
        return v;
    }

    inline Modular operator +(Modular x) const {
        return x += *this;
    }

    inline Modular operator -(Modular x) const {
        return *this + (-x);
    }

    inline Modular operator *(Modular x) const {
        return x *= *this;
    }

    inline Modular operator /(Modular x) const {
        return (*this) * x.pow(-1);
    } 

    inline bool operator ==(Modular x) const {
        return value == x.value;
    }

    inline bool operator !=(Modular x) const {
        return value != x.value;
    }

    inline explicit operator int() const {
        return value;
    }

    Modular fact() const { 
        Modular x(1);
        for(int i = 1; i <= value; ++i) x *= i;
        return x;
    }

    friend ostream& operator <<(ostream& os, Modular x) {
        return os << x.value;
    }

    friend istream& operator >>(istream& is, Modular& x) {
        is >> x.value; x.value %= mod; return is;
    }
};

int Modular::mod{1000000007};

namespace combinatorics {
    constexpr int MAXN{200000};
    array<Modular,  MAXN + 1> fact, ifact;

    void init() {
        fact[0] = ifact[0] = 1;
        for(int i = 1; i <= MAXN; ++i)
            fact[i] = fact[i - 1] * i, ifact[i] = fact[i].pow(-1);
    }

    inline Modular nCr(int n, int r) {
        return fact[n] * ifact[n - r] * ifact[r];
    }

    inline Modular nPr(int n, int r) {
        return fact[n] * ifact[n - r];
    }
} // namespace combinatorics


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    
    #ifdef DEBUG
    freopen("debug", "w", stderr);
    #endif

    combinatorics::init();

    int N, K; cin >> N >> K;
    vector<int> A(N); for(int& a : A) cin >> a;
    vector<int> P(K); for(int& p : P) cin >> p, --p;

    assert(ll(N) * K <= 2000 * 2000);
    
    auto get_suffix = [&](int p) {
        queue<int> v;
        for(int i = p; i < N;) {
            int x{A[i++]};
            for(; i < N && A[i] > x; ++i);
            v.push(x);
        }
        return v;
    };

    auto get_prefix = [&](int p) {
        queue<int> v;
        for(int i = p; i >= 0;) {
            int x{A[i--]};
            for(; i >= 0 && A[i] > x; --i);
            v.push(x);
        }
        return v;
    };

    auto solve_for = [&](int p) {
        queue<int> pref{get_prefix(p - 1)};
        queue<int> suff{get_suffix(p + 1)};
        Modular ans{1};
        while(!pref.empty() && !suff.empty()) {
            int l{}, r{}, x{max(pref.front(), suff.front())};
            while(!pref.empty() && pref.front() == x) ++l, pref.pop();
            while(!suff.empty() && suff.front() == x) ++r, suff.pop();
            ans *= combinatorics::nCr(l + r, r);
        }
        return ans;
    };

    for(int& p : P) cout << solve_for(p) << '\n';

    #ifdef DEBUG
    dbg::dout << "\nExecution time: " << clock() * 1000 / CLOCKS_PER_SEC  << "ms" << endl;
    #endif

    return 0;
}

• Subtask 1: 22 / 22
• Subtask 2: 38 / 38
• Subtask 3: 0 / 40