Language: C++

#include <bits/stdc++.h>
using namespace std;

// template {{{
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define lb lower_bound
#define ub upper_bound
#define f first
#define s second
#define resz resize

#define sz(x) int((x).size())
#define all(x) (x).begin(), (x).end()

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)

#define sort_by(x, y) sort(all(x), [&](const auto& a, const auto& b) { return y; })

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vb = vector<bool>;
using vd = vector<double>;
using vs = vector<string>;

using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;

using vpii = vector<pii>;
using vvpii = vector<vpii>;
using vpll = vector<pll>;
using vvpll = vector<vpll>;
using vpdd = vector<pdd>;
using vvpdd = vector<vpdd>;

template<typename T> void ckmin(T& a, const T& b) { a = min(a, b); }
template<typename T> void ckmax(T& a, const T& b) { a = max(a, b); }

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

namespace __input {
    template<class T1, class T2> void re(pair<T1,T2>& p);
    template<class T> void re(vector<T>& a);
    template<class T, size_t SZ> void re(array<T,SZ>& a);

    template<class T> void re(T& x) { cin >> x; }
    void re(double& x) { string t; re(t); x = stod(t); }
    template<class Arg, class... Args> void re(Arg& first, Args&... rest) {
        re(first); re(rest...);
    }

    template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.f,p.s); }
    template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
    template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
}
using namespace __input;

namespace __output {
    template<class T1, class T2> void pr(const pair<T1,T2>& x);
    template<class T, size_t SZ> void pr(const array<T,SZ>& x);
    template<class T> void pr(const vector<T>& x);
    template<class T> void pr(const deque<T>& x);
    template<class T> void pr(const set<T>& x);
    template<class T1, class T2> void pr(const map<T1,T2>& x);

    template<class T> void pr(const T& x) { cout << x; }
    template<class Arg, class... Args> void pr(const Arg& first, const Args&... rest) {
        pr(first); pr(rest...);
    }

    template<class T1, class T2> void pr(const pair<T1,T2>& x) {
        pr("{",x.f,", ",x.s,"}");
    }
    template<class T, bool pretty = true> void prContain(const T& x) {
        if (pretty) pr("{");
        bool fst = 1; for (const auto& a: x) pr(!fst?pretty?", ":" ":"",a), fst = 0;
        if (pretty) pr("}");
    }
    template<class T> void pc(const T& x) { prContain<T, false>(x); pr("\n"); }
    template<class T, size_t SZ> void pr(const array<T,SZ>& x) { prContain(x); }
    template<class T> void pr(const vector<T>& x) { prContain(x); }
    template<class T> void pr(const deque<T>& x) { prContain(x); }
    template<class T> void pr(const set<T>& x) { prContain(x); }
    template<class T1, class T2> void pr(const map<T1,T2>& x) { prContain(x); }

    void ps() { pr("\n"); }
    template<class Arg> void ps(const Arg& first) {
        pr(first); ps();
    }
    template<class Arg, class... Args> void ps(const Arg& first, const Args&... rest) {
        pr(first," "); ps(rest...);
    }
}
using namespace __output;

#define TRACE(x) x
#define __pn(x) pr(#x, " = ")
#define pd(...) __pn((__VA_ARGS__)), ps(__VA_ARGS__), cout << flush

namespace __algorithm {
    template<typename T> void dedup(vector<T>& v) {
        sort(all(v)); v.erase(unique(all(v)), v.end());
    }
    template<typename T> typename vector<T>::iterator find(vector<T>& v, const T& x) {
        auto it = lower_bound(all(v), x); return it != v.end() && *it == x ? it : v.end();
    }
    template<typename T> size_t index(vector<T>& v, const T& x) {
        auto it = find(v, x); assert(it != v.end() && *it == x); return it - v.begin();
    }
    template<typename C, typename T, typename OP> vector<T> prefixes(const C& v, T id, OP op) {
        vector<T> r(sz(v)+1, id); F0R (i, sz(v)) r[i+1] = op(r[i], v[i]); return r;
    }
    template<typename C, typename T, typename OP> vector<T> suffixes(const C& v, T id, OP op) {
        vector<T> r(sz(v)+1, id); F0Rd (i, sz(v)) r[i] = op(v[i], r[i+1]); return r;
    }
}
using namespace __algorithm;

struct monostate {
    friend istream& operator>>(istream& is, const __attribute__((unused))monostate& ms) { return is; }
    friend ostream& operator<<(ostream& os, const __attribute__((unused))monostate& ms) { return os; }
} ms;

template<typename W=monostate> struct wedge {
    int u, v, i; W w;
    wedge<W>(int _u=-1, int _v=-1, int _i=-1) : u(_u), v(_v), i(_i) {}
    int operator[](int loc) const { return u ^ v ^ loc; }
    friend void re(wedge& e) { re(e.u, e.v, e.w); --e.u, --e.v; }
    friend void pr(const wedge& e) { pr(e.u, "<-", e.w, "->", e.v); }
};

namespace __io {
    void setIn(string s) { freopen(s.c_str(),"r",stdin); }
    void setOut(string s) { freopen(s.c_str(),"w",stdout); }
    void setIO(string s = "") {
        ios_base::sync_with_stdio(0); cin.tie(0);
        cout << fixed << setprecision(15);
        if (sz(s)) { setIn(s+".in"), setOut(s+".out"); }
    }
}
using namespace __io;
// }}}

// sparse_table {{{
template<typename T, typename F> struct sparse_table {
    int SZ;
    F tt; // idempotent
    vector<T> table;

    T& entry(int l, int i) { return table[l * SZ + i]; }
    const T& entry(int l, int i) const { return table[l * SZ + i]; }

    sparse_table() {}
    sparse_table(const vector<T>& elts, F _tt) : SZ(sz(elts)), tt(_tt) {
        const int L = 32 - __builtin_clz(max(SZ - 1, 1));
        table.resize(L * SZ);
        copy(all(elts), table.begin());

        for (int l = 0; l + 1 < L; l++) {
            for (int i = 0; i < SZ; i++) {
                entry(l + 1, i) = entry(l, i);
                if (i + (1 << l) < SZ)
                    entry(l + 1, i) = tt(entry(l + 1, i), entry(l, i + (1 << l)));
            }
        }
    }

    // Accumulates the elements at indices in [i, j) in O(1)
    T operator()(int i, int j) const {
        assert(0 <= i && i < j && j <= SZ);
        int l = j - i - 1 ? 31 - __builtin_clz(j - i - 1) : 0;
        return tt(entry(l, i), entry(l, j - (1 << l)));
    }
};
// }}}

// union_find {{{
struct uf_monostate {
    uf_monostate(__attribute__((unused)) int id) {}
    void merge(__attribute__((unused)) uf_monostate& o,
            __attribute__((unused)) const monostate& e) {}
};

template<typename T = uf_monostate, typename E = monostate>
struct union_find {
    struct node {
        int par, rnk, size; T state;
        node(int id = 0) : par(id), rnk(0), size(1), state(id) {}
        void merge(node& o, E& e) {
            if (rnk == o.rnk) rnk++;
            if (size < o.size) swap(state, o.state);
            size += o.size;
            state.merge(o.state, e);
        }
    };

    vector<node> uf;
    union_find(int N = 0) : uf(N) {
        for (int i = 0; i < N; i++)
            uf[i] = node(i);
    }

    int rep(int i) {
        if (i != uf[i].par)
            uf[i].par = rep(uf[i].par);
        return uf[i].par;
    }

    bool unio(int a, int b, E& e = ms) {
        a = rep(a), b = rep(b);
        if (a == b) return false;
        if (uf[a].rnk < uf[b].rnk) swap(a, b);
        uf[a].merge(uf[b], e);
        uf[b].par = a;
        return true;
    }

    T& state(int i) { return uf[rep(i)].state; }
};
// }}}

int main() {
    setIO();

    int N, K; re(N, K); vi a(N); re(a);

    sparse_table maxt(a, [](int a, int b){ return max(a, b); });
    sparse_table mint(a, [](int a, int b){ return min(a, b); });

    int ans = N - K + 1;

    union_find uf(N);
    FOR (i, 1, N - K + 1) {
        if (mint(i - 1, i - 1 + K) == a[i-1] && maxt(i, i + K) == a[i+K-1])
            ans -= uf.unio(i - 1, i);
    }

    bool f = false;
    int str = 1;
    FOR (i, 1, N + 1) {
        if (i == N || a[i] < a[i-1]) {
            if (str >= K) {
                if (!f) f = true;
                else ans--;
            }
            str = 1;
        } else str++;
    }

    ps(ans);

    return 0;
}



Compiler output:
a.cc:134:21: error: reference to 'monostate' is ambiguous
  134 | template<typename W=monostate> struct wedge {
      |                     ^~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:80,
                 from a.cc:1:
/usr/include/c++/14/variant:1237:10: note: candidates are: 'struct std::monostate'
 1237 |   struct monostate { };
      |          ^~~~~~~~~
a.cc:129:8: note:                 'struct monostate'
  129 | struct monostate {
      |        ^~~~~~~~~
a.cc:191:43: error: reference to 'monostate' is ambiguous
  191 |             __attribute__((unused)) const monostate& e) {}
      |                                           ^~~~~~~~~
/usr/include/c++/14/variant:1237:10: note: candidates are: 'struct std::monostate'
 1237 |   struct monostate { };
      |          ^~~~~~~~~
a.cc:129:8: note:                 'struct monostate'
  129 | struct monostate {
      |        ^~~~~~~~~
a.cc:194:50: error: reference to 'monostate' is ambiguous
  194 | template<typename T = uf_monostate, typename E = monostate>
      |                                                  ^~~~~~~~~
/usr/include/c++/14/variant:1237:10: note: candidates are: 'struct std::monostate'
 1237 |   struct monostate { };
      |          ^~~~~~~~~
a.cc:129:8: note:                 'struct monostate'
  129 | struct monostate {
      |        ^~~~~~~~~
a.cc: In function 'int main()':
a.cc:242:20: error: class template argument deduction failed:
  242 |     union_find uf(N);
      |                    ^
a.cc:242:20: error: no matching function for call to 'union_find(int&)'
a.cc:208:5: note: candidate: 'template<class T, class E> union_find(int)-> union_find<T, E>'
  208 |     union_find(int N = 0) : uf(N) {
      |     ^~~~~~~~~~
a.cc:208:5: note:   template argument deduction/substitution failed:
a.cc:195:8: note: candidate: 'template<class T, class E> union_find(union_find<T, E>)-> union_find<T, E>'
  195 | struct union_find {
      |        ^~~~~~~~~~
a.cc:195:8: note:   template argument deduction/substitution failed:
a.cc:242:20: note:   mismatched types 'union_find<T, E>' and 'int'
  242 |     union_find uf(N);
      |                    ^