CSES Bracket Sequences I – I wasted time, and now doth time waste me

// compile: make data
// run: ./data < data.in
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#include <debug/codeforces.h>
#define debug(x...) _debug_print(#x, x);
#define Debug(x...) _debug_print_format(#x, x);
std::ifstream terminal("/dev/tty");
#define PP cerr<<"\033[1;30mpause...\e[0m",terminal.ignore();
#else
#define debug(x...)
#define Debug(x...)
#define PP
#endif
template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;}
#define VI vector<int>
#define VII vector<vector<int>>
#define VIII vector<vector<vector<int>>>
#define rep(i,a,b) for(int i=(a);i<(int)(b);++i)
#define sz(v) ((int)(v).size())
#define print(...) print_(__VA_ARGS__);
#define FIND(a, x) ((find(a.begin(),a.end(),(x))!=a.end())?1:0)
#define cmin(x,...) x=min({(x), __VA_ARGS__})
#define cmax(x,...) x=max({(x), __VA_ARGS__})
#define INTMAX (int)(9223372036854775807)
#define INF (int)(1152921504606846976)
#define NaN (int)(0x8b88e1d0595d51d1)
#define double long double
#define int long long
#define uint unsigned long long
#define MAXN 200010

namespace mathlib {
    namespace internal {
        #ifndef _MSC_VER
        template <class T> using is_signed_int128 = typename std::conditional<std::is_same<T, __int128_t>::value || std::is_same<T, __int128>::value, std::true_type, std::false_type>::type;
        template <class T> using is_unsigned_int128 = typename std::conditional<std::is_same<T, __uint128_t>::value || std::is_same<T, unsigned __int128>::value, std::true_type, std::false_type>::type;
        template <class T> using make_unsigned_int128 = typename std::conditional<std::is_same<T, __int128_t>::value, __uint128_t, unsigned __int128>;
        template <class T> using is_integral = typename std::conditional<std::is_integral<T>::value || is_signed_int128<T>::value || is_unsigned_int128<T>::value, std::true_type, std::false_type>::type;
        template <class T> using is_signed_int = typename std::conditional<(is_integral<T>::value && std::is_signed<T>::value) || is_signed_int128<T>::value, std::true_type, std::false_type>::type;
        template <class T> using is_unsigned_int = typename std::conditional<(is_integral<T>::value && std::is_unsigned<T>::value) || is_unsigned_int128<T>::value, std::true_type, std::false_type>::type;
        template <class T> using to_unsigned = typename std::conditional< is_signed_int128<T>::value, make_unsigned_int128<T>, typename std::conditional<std::is_signed<T>::value, std::make_unsigned<T>, std::common_type<T>>::type>::type;
        #else
        template <class T> using is_integral = typename std::is_integral<T>;
        template <class T> using is_signed_int = typename std::conditional<is_integral<T>::value && std::is_signed<T>::value, std::true_type, std::false_type>::type;
        template <class T> using is_unsigned_int = typename std::conditional<is_integral<T>::value && std::is_unsigned<T>::value, std::true_type, std::false_type>::type;
        template <class T> using to_unsigned = typename std::conditional<is_signed_int<T>::value, std::make_unsigned<T>, std::common_type<T>>::type;
        #endif
        template <class T> using is_signed_int_t = std::enable_if_t<is_signed_int<T>::value>;
        template <class T> using is_unsigned_int_t = std::enable_if_t<is_unsigned_int<T>::value>;
        template <class T> using to_unsigned_t = typename to_unsigned<T>::type;
        constexpr long long safe_mod(long long x, long long m) {x %= m; if (x < 0) x += m; return x; }
        struct barrett {
            unsigned int _m;
            unsigned long long im;
            explicit barrett(unsigned int m) : _m(m), im((unsigned long long)(-1) / m + 1) {}
            unsigned int umod() const { return _m; }
            unsigned int mul(unsigned int a, unsigned int b) const {
                unsigned long long z = a;
                z *= b;
                #ifdef _MSC_VER
                unsigned long long x;
                _umul128(z, im, &x);
                #else
                unsigned long long x = (unsigned long long)(((unsigned __int128)(z)*im) >> 64);
                #endif
                unsigned long long y = x * _m;
                return (unsigned int)(z - y + (z < y ? _m : 0));
            }
        };
        constexpr std::pair<long long, long long> inv_gcd(long long a, long long b) {
            a = safe_mod(a, b);
            if (a == 0) return {b, 0};
            long long s = b, t = a;
            long long m0 = 0, m1 = 1;
            while (t) {
                long long u = s / t;
                s -= t * u;
                m0 -= m1 * u;
                auto tmp = s;
                s = t;
                t = tmp;
                tmp = m0;
                m0 = m1;
                m1 = tmp;
            }
            if (m0 < 0) m0 += b / s;
            return {s, m0};
        }
        constexpr long long pow_mod_constexpr(long long x, long long n, int m) {
            if (m == 1) return 0;
            unsigned int _m = (unsigned int)(m);
            unsigned long long r = 1;
            unsigned long long y = safe_mod(x, m);
            while (n) {if (n & 1) r = (r * y) % _m; y = (y * y) % _m; n >>= 1; }
            return r;
        }
        constexpr bool is_prime_constexpr(int n) {
            if (n <= 1) return false;
            if (n == 2 || n == 7 || n == 61) return true;
            if (n % 2 == 0) return false;
            long long d = n - 1;
            while (d % 2 == 0) d /= 2;
            constexpr long long bases[3] = {2, 7, 61};
            for (long long a : bases) {
                long long t = d;
                long long y = pow_mod_constexpr(a, t, n);
                while (t != n - 1 && y != 1 && y != n - 1) {y = y * y % n; t <<= 1; }
                if (y != n - 1 && t % 2 == 0) return false;
            }
            return true;
        }
        template <int n> constexpr bool is_prime = is_prime_constexpr(n);
        struct modint_base {};
        struct static_modint_base : modint_base {};
        template <class T> using is_modint = std::is_base_of<modint_base, T>;
        template <class T> using is_modint_t = std::enable_if_t<is_modint<T>::value>;
    }
    template <int m, std::enable_if_t<(1 <= m)>* = nullptr>
    struct static_modint : internal::static_modint_base {
        using mint = static_modint;
        public:
            static constexpr int mod() { return m; }
            static mint raw(int v) {mint x; x._v = v; return x; }
            static_modint() : _v(0) {}
            template <class T, internal::is_signed_int_t<T>* = nullptr>
            static_modint(T v) {long long x = (long long)(v % (long long)(umod())); if (x < 0) x += umod(); _v = (unsigned int)(x); }
            template <class T, internal::is_unsigned_int_t<T>* = nullptr>
            static_modint(T v) {_v = (unsigned int)(v % umod()); }
            unsigned int val() const { return _v; }
            mint& operator++() {_v++; if (_v == umod()) _v = 0; return *this; }
            mint& operator--() {if (_v == 0) _v = umod(); _v--; return *this; }
            mint operator++(int32_t) {mint result = *this; ++*this; return result; }
            mint operator--(int32_t) {mint result = *this; --*this; return result; }
            mint& operator+=(const mint& rhs) {_v += rhs._v; if (_v >= umod()) _v -= umod(); return *this; }
            mint& operator-=(const mint& rhs) {_v -= rhs._v; if (_v >= umod()) _v += umod(); return *this; }
            mint& operator*=(const mint& rhs) {unsigned long long z = _v; z *= rhs._v; _v = (unsigned int)(z % umod()); return *this; }
            mint& operator/=(const mint& rhs) {return *this = *this * rhs.inv(); }
            mint operator+() const { return *this; }
            mint operator-() const { return mint() - *this; }
            mint pow(long long n) const {
                assert(0 <= n);
                mint x = *this, r = 1;
                while (n) {if (n & 1) r *= x; x *= x; n >>= 1; }
                return r;
            }
            mint inv() const {
                if (prime) {assert(_v); return pow(umod() - 2); }
                else {auto eg = internal::inv_gcd(_v, m); assert(eg.first == 1); return eg.second; }
            }
            friend mint operator+(const mint& lhs, const mint& rhs) {return mint(lhs) += rhs; }
            friend mint operator-(const mint& lhs, const mint& rhs) {return mint(lhs) -= rhs; }
            friend mint operator*(const mint& lhs, const mint& rhs) {return mint(lhs) *= rhs; }
            friend mint operator/(const mint& lhs, const mint& rhs) {return mint(lhs) /= rhs; }
            friend bool operator==(const mint& lhs, const mint& rhs) {return lhs._v == rhs._v; }
            friend bool operator!=(const mint& lhs, const mint& rhs) {return lhs._v != rhs._v; }
        private:
            unsigned int _v;
            static constexpr unsigned int umod() { return m; }
            static constexpr bool prime = internal::is_prime<m>;
    };
};
using mint = mathlib::static_modint<1000000007>;

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    int n; cin >> n;
    if (n & 1) {
        cout << 0 << '\n';
        return 0;
    }
    n >>= 1;
    vector<mint> fact(2*n+1);
    fact[0] = 1; rep(i, 1, 2*n+1) fact[i] = fact[i-1] * i;
    auto comb = [&](int n, int k) {
        mint res = fact[n];
        res /= fact[k];
        res /= fact[n-k];
        return res;
    };
    mint ans = comb(2*n, n);
    ans -= comb(2*n, n-1);
    cout << ans.val() << endl;

    return 0;
}
Comments

ace58casino

2 months ago
2025-12-06 2:34:17

Ace58casino, that’s the one! Been hitting the tables here for a while now. Good payouts and some pretty sweet bonuses. You can get started at ace58casino.
gà chọi c1 thomo

2 months ago
2025-12-19 13:49:22

Thomo fans, gà chọi c1 thomo seems to be the spot. Just passing it along, alright?
q8bet

1 month ago
2025-12-29 6:17:36

Q8Bet looks interesting. I wonder if there’s any relationship with any Qatari investments in sports! Anyway the site is smooth enough. Will check how’s their sports promotions and compare it with others. Worth a look: q8bet
Comments

Send Comment Edit Comment
