結果

問題 No.1371 交換門松列・松
ユーザー haruki_Kharuki_K
提出日時 2021-01-29 22:39:43
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 79 ms / 4,000 ms
コード長 10,553 bytes
コンパイル時間 2,321 ms
コンパイル使用メモリ 214,876 KB
最終ジャッジ日時 2025-01-18 09:36:11
ジャッジサーバーID
（参考情報） 		judge1 / judge1
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 29
権限があれば一括ダウンロードができます

ソースコード

diff # 

// >>> TEMPLATES
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
#define int ll
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define repR(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep1R(i, n) for (int i = (int)(n); i >= 1; i--)
#define loop(i, a, B) for (int i = a; i B; i++)
#define loopR(i, a, B) for (int i = a; i B; i--)
#define all(x) begin(x), end(x)
#define allR(x) rbegin(x), rend(x)
#define rng(x, l, r) begin(x) + (l), begin(x) + (r)
#define pb push_back
#define eb emplace_back
#define fst first
#define snd second
template <class A, class B> auto mp(A &&a, B &&b) { return make_pair(forward<A>(a), forward<B>(b)); }
template <class... T> auto mt(T&&... x) { return make_tuple(forward<T>(x)...); }
template <class Int> auto constexpr inf_ = numeric_limits<Int>::max()/2-1;
auto constexpr INF32 = inf_<int32_t>;
auto constexpr INF64 = inf_<int64_t>;
auto constexpr INF   = inf_<int>;
#ifdef LOCAL
#include "debug.hpp"
#else
#define dump(...) (void)(0)
#define say(x) (void)(0)
#define debug if (0)
#endif
template <class T, class Comp> struct pque : priority_queue<T, vector<T>, Comp> { vector<T> &data() { return this->c; } void clear() { this->c.clear(); } };
template <class T> using pque_max = pque<T, less<T>>;
template <class T> using pque_min = pque<T, greater<T>>;
template <class T, class = typename T::iterator, enable_if_t<!is_same<T, string>::value, int> = 0>
ostream& operator<<(ostream& os, T const& a) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, size_t N, enable_if_t<!is_same<T, char>::value, int> = 0>
ostream& operator<<(ostream& os, const T (&a)[N]) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, class = decltype(begin(declval<T&>())), class = typename enable_if<!is_same<T, string>::value>::type>
istream& operator>>(istream& is, T &a) { for (auto& x : a) is >> x; return is; }
template <class T, class S> ostream& operator<<(ostream& os, pair<T, S> const& p) { return os << p.first << " " << p.second; }
template <class T, class S> istream& operator>>(istream& is, pair<T, S>& p) { return is >> p.first >> p.second; }
struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup;
template <class F> struct FixPoint : private F {
    constexpr FixPoint(F&& f) : F(forward<F>(f)) {}
    template <class... T> constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward<T>(x)...); }
};
struct MakeFixPoint { template <class F> constexpr auto operator|(F&& f) const { return FixPoint<F>(forward<F>(f)); } };
#define MFP MakeFixPoint()|
#define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__)
template <class T, size_t d> struct vec_impl {
    using type = vector<typename vec_impl<T, d-1>::type>;
    template <class... U> static type make_v(size_t n, U&&... x) { return type(n, vec_impl<T, d-1>::make_v(forward<U>(x)...)); }
};
template <class T> struct vec_impl<T, 0> { using type = T; static type make_v(T const& x = {}) { return x; } };
template <class T, size_t d = 1> using vec = typename vec_impl<T, d>::type;
template <class T, size_t d = 1, class... Args> auto make_v(Args&&... args) { return vec_impl<T, d>::make_v(forward<Args>(args)...); }
template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T, class U> constexpr bool chmin(T& x, U const& y) { if (x > y) { x = y; return true; } return false; }
template <class T, class U> constexpr bool chmax(T& x, U const& y) { if (x < y) { x = y; return true; } return false; }
template <class It> constexpr auto sumof(It b, It e) { return accumulate(b, e, typename iterator_traits<It>::value_type{}); }
template <class T> int sz(T const& x) { return x.size(); }
template <class C, class T> int lbd(C const& v, T const& x) { return lower_bound(begin(v), end(v), x)-begin(v); }
template <class C, class T> int ubd(C const& v, T const& x) { return upper_bound(begin(v), end(v), x)-begin(v); }
const int dx[] = { 1, 0, -1, 0, 1, -1, -1, 1 };
const int dy[] = { 0, 1, 0, -1, 1, 1, -1, -1 };
constexpr int popcnt(ll x) { return __builtin_popcountll(x); }
template <class A, class B> pair<A, B> operator+(pair<A, B> const& p, pair<A, B> const& q) { return { p.first + q.first, p.second + q.second }; }
template <class A, class B> pair<A, B> operator-(pair<A, B> const& p, pair<A, B> const& q) { return { p.first - q.first, p.second - q.second }; }
mt19937_64 seed_{random_device{}()};
template <class Int> Int rand(Int a, Int b) { return uniform_int_distribution<Int>(a, b)(seed_); }
i64 irand(i64 a, i64 b) { return rand<i64>(a, b); } // [a, b]
u64 urand(u64 a, u64 b) { return rand<u64>(a, b); } //
template <class It> void shuffle(It l, It r) { shuffle(l, r, seed_); }
// <<<
// >>> BIT 2D
template <class T, class Int = int> struct BIT2D {
    vector<pair<Int, Int>> pos;
    vector<Int> xs, ys;
    vector<T> bit;
    vector<size_t> idx;
    bool built = false;

    BIT2D() {}
    void add_point(Int x, Int y) {
        pos.emplace_back(x, y);
        built = false;
    }
    void build() {
        auto make_unique = [&](auto &v) { v.resize(unique(v.begin(), v.end())-v.begin()); };
        sort(pos.begin(), pos.end());
        make_unique(pos);
        for (auto [x, y] : pos) xs.push_back(x);
        make_unique(xs);
        int n = xs.size();
        idx.resize(n+1);
        vector<vector<Int>> z(n);
        int i = 0;
        for (auto [x, y] : pos) {
            if (xs[i] < x) i++;
            z[i].push_back(y);
        }
        for (i = 0; i < n; i++) {
            make_unique(z[i]);
            int j = i | (i + 1);
            if (j >= n) continue;
            int A = z[j].size(), B = z[i].size();
            z[j].reserve(A + B);
            copy(z[i].begin(), z[i].end(), back_inserter(z[j]));
            inplace_merge(z[j].begin(), z[j].begin() + A, z[j].end());
        }
        for (i = 0; i < n; i++) {
            copy(z[i].begin(), z[i].end(), back_inserter(ys));
            idx[i+1] = ys.size();
        }
        bit.resize(idx.back());
        built = true;
    }
    void add(Int x, Int y, T const& val) {
        assert(built);
        int i = lower_bound(xs.begin(), xs.end(), x) - xs.begin();
        assert(i < (int)xs.size() and xs[i] == x);
        for ( ; i < (int)xs.size(); i |= i + 1) {
            auto it = lower_bound(ys.begin() + idx[i], ys.begin() + idx[i+1], y);
            assert(it != ys.end() and *it == y);
            int j = it - (ys.begin() + idx[i]);
            for ( ; idx[i] + j < idx[i+1]; j |= j + 1) {
                bit[idx[i] + j] += val;
            }
        }
    }
    T sum(Int xr, Int yl, Int yr) const {
        assert(built);
        int i = lower_bound(xs.begin(), xs.end(), xr) - xs.begin();
        T s = 0;
        for (i-- ; i >= 0; i = (i & (i + 1)) - 1) {
            int j = lower_bound(ys.begin() + idx[i], ys.begin() + idx[i+1], yr) - (ys.begin() + idx[i]);
            for (j-- ; j >= 0; j = (j & (j + 1)) - 1) {
                s += bit[idx[i] + j];
            }
            j = lower_bound(ys.begin() + idx[i], ys.begin() + idx[i+1], yl) - (ys.begin() + idx[i]);
            for (j-- ; j >= 0; j = (j & (j + 1)) - 1) {
                s -= bit[idx[i] + j];
            }
        }
        return s;
    }
    T sum(Int xl, Int xr, Int yl, Int yr) const {
        return sum(xr, yl, yr) - sum(xl, yl, yr);
    }
    T get(Int x, Int y) const { return sum(x, x+1, y, y+1); }
    vector<T> dat() const {
        assert(built);
        vector<T> ret;
        for (auto [x, y] : pos) ret.push_back(get(x, y));
        return ret;
    }
};
// <<<
// >>> BIT

struct BIT {
    int n;
    vector<int> v; // use v[1..n]
    BIT(int n = 0) : n(n), v(n+1) {}
    int size() const { return n; }
    int operator[](int i) const { return get(i); }
    int get(int i) const { return sum(i+1)-sum(i); }
    void set(int i, int x) { add(i, x-get(i)); }
    void add(int i, int x) {
        assert(0 <= i); assert(i < n);
        for (i++; i <= n; i += i&(-i)) v[i] += x;
    }
    int sum(int r) const { // [0, r)
        assert(0 <= r); assert(r <= n);
        int s = 0;
        for (int i = r; i > 0; i -= i&(-i)) s += v[i];
        return s;
    }
    int sum(int l, int r) const { // [l, r)
        return sum(r)-sum(l);
    }
    // lower_bound({sum(0), sum(1), ..., sum(n)}, x)
    int lower_bound(int x) const {
        if (x <= 0) return 0;
        int s = 0, i = 0, w = 1;
        while (2*w <= n) w *= 2;
        for ( ; w; w >>= 1) {
            if (i+w <= n && s+v[i+w] < x) {
                s += v[i+w];
                i += w;
            }
        }
        return i+1;
    }
    int upper_bound(int x) const {
        if (x < 0) return 0;
        int s = 0, i = 0, w = 1;
        while (2*w <= n) w *= 2;
        for ( ; w; w >>= 1) {
            if (i+w <= n && s+v[i+w] <= x) {
                s += v[i+w];
                i += w;
            }
        }
        return i+1;
    }
};

// <<<

int32_t main() {
    int n; cin >> n;
    vector<int> a(n);
    rep (i, n) cin >> a[i], --a[i];
    if (a[0] > a[1]) rep (i, n) a[i] = n-1-a[i];

    vector<pair<int, int>> p[2];
    rep (i, n) {
        if (i % 2 == 0) {
            int L = i-1 >= 0 ? a[i-1] : INF;
            int R = i+1 < n ? a[i+1] : INF;
            assert(a[i] <= min(L, R)-1);
            p[0].eb(a[i], min(L, R)-1);
        } else {
            int L = i-1 >= 0 ? a[i-1] : -INF;
            int R = i+1 < n ? a[i+1] : -INF;
            assert(a[i] >= max(L, R) + 1);
            p[1].eb(a[i], max(L, R) + 1);
        }
    }

    int ans = 0;
    {
        BIT bit(n);
        sort(all(p[0]));
        for (auto [x, y] : p[0]) {
            ans += bit.sum(x, n);
            bit.add(y, +1);
        }
    }
    dump(ans);
    {
        BIT bit(n);
        sort(all(p[1]));
        for (auto [x, y] : p[1]) {
            ans += bit.sum(y, n);
            bit.add(x, +1);
        }
    }
    dump(ans);

    vector<tuple<int, int, int>> es;
    for (auto [x, y] : p[1]) es.eb(x, -1, y);
    for (auto [x, y] : p[0]) es.eb(y, +1, x);
    sort(all(es));
    BIT bit(n+1);
    for (auto [x, t, y] : es) {
        if (t < 0) {
            bit.add(y, +1);
        } else {
            ans += bit.sum(0, y+1);
        }
    }

    cout << ans << "\n";

}
0