9209c568.cpp

#include <bits/stdc++.h>
#define watch(x) std::cout << "$ LINE @" << __LINE__ << " FUNC @" << __FUNCTION__ << "\n$ " \
                           << (#x) << ": " << x << std::endl

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;

template <typename Tp>
inline void read(Tp &x)
{
    static char c;
    static bool neg;
    x = 0, c = getchar(), neg = false;
    for (; !isdigit(c); c = getchar())
    {
        if (c == '-')
        {
            neg = true;
        }
    }
    for (; isdigit(c); c = getchar())
    {
        x = x * 10 + c - '0';
    }
    if (neg)
    {
        x = -x;
    }
}

const int N = 2e5 + 5;
const int INF = 0x3f3f3f3f;

int n, k;
int a[N];

unordered_map<int, int> front, back;

inline void add(unordered_map<int, int> &mp, int x)
{
    ++mp[x];
}
inline void del(unordered_map<int, int> &mp, int x)
{
    auto iter = mp.find(x);
    if (iter->second == 1)
    {
        mp.erase(iter);
    }
    else
    {
        --iter->second;
    }
}

int main()
{
    read(n), read(k);
    for (int i = 1; i <= n; ++i)
    {
        read(a[i]);
    }
    add(front, a[1]);
    for (int i = 3; i <= n; ++i)
    {
        add(back, a[i]);
    }
    ll ans = 0;
    ll fx, bx;
    for (int i = 2; i <= n - 1; ++i)
    {
        if (a[i] % k == 0)
        {
            fx = (ll)a[i] / k, bx = (ll)a[i] * k;
            if (bx < (ll)INF)
            {
                auto fi = front.find((int)fx), bi = back.find((int)bx);
                if (fi != front.end() && bi != back.end())
                {
                    ans += (ll)fi->second * bi->second;
                }
            }
        }
        add(front, a[i]);
        del(back, a[i + 1]);
    }
    printf("%lld\n", ans);
    return 0;
}