Language: C

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

#define rep(i,n) for(long long i = 0; i < (long long)(n); i++)
#define repi(i,a,b) for(long long i = (long long)(a); i < (long long)(b); i++)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second
#define mt make_tuple
#define mp make_pair
template<class T1, class T2> bool chmin(T1 &a, T2 b) { return b < a && (a = b, true); }
template<class T1, class T2> bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
#define exists find_if
#define forall all_of

using ll = long long; using vll = vector<ll>; using vvll = vector<vll>; using P = pair<ll, ll>;
using ld = long double;  using vld = vector<ld>; 
using vi = vector<int>; using vvi = vector<vi>; vll conv(vi& v) { vll r(v.size()); rep(i, v.size()) r[i] = v[i]; return r; }
using Pos = complex<double>;

template <typename T, typename U> ostream &operator<<(ostream &o, const pair<T, U> &v) {  o << "(" << v.first << ", " << v.second << ")"; return o; }
template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
template<class Ch, class Tr, class Tuple, size_t... Is>
void print_tuple(basic_ostream<Ch,Tr>& os, Tuple const& t, seq<Is...>){ using s = int[]; (void)s{0, (void(os << (Is == 0? "" : ", ") << get<Is>(t)), 0)...}; }
template<class Ch, class Tr, class... Args> 
auto operator<<(basic_ostream<Ch, Tr>& os, tuple<Args...> const& t) -> basic_ostream<Ch, Tr>& { os << "("; print_tuple(os, t, gen_seq<sizeof...(Args)>()); return os << ")"; }
ostream &operator<<(ostream &o, const vvll &v) { rep(i, v.size()) { rep(j, v[i].size()) o << v[i][j] << " "; o << endl; } return o; }
template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { o << '['; rep(i, v.size()) o << v[i] << (i != v.size()-1 ? ", " : ""); o << "]";  return o; }
template <typename T>  ostream &operator<<(ostream &o, const set<T> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T, typename U>  ostream &operator<<(ostream &o, const map<T, U> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T, typename U, typename V>  ostream &operator<<(ostream &o, const unordered_map<T, U, V> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it; o << "]";  return o; }
vector<int> range(const int x, const int y) { vector<int> v(y - x + 1); iota(v.begin(), v.end(), x); return v; }
template <typename T> istream& operator>>(istream& i, vector<T>& o) { rep(j, o.size()) i >> o[j]; return i;}
string bits_to_string(ll input, ll n=64) { string s; rep(i, n) s += '0' + !!(input & (1ll << i)); reverse(all(s)); return s; }

template <typename T> unordered_map<T, ll> counter(vector<T> vec){unordered_map<T, ll> ret; for (auto&& x : vec) ret[x]++; return ret;};
string substr(string s, P x) {return s.substr(x.fi, x.se - x.fi); }
struct ci : public iterator<forward_iterator_tag, ll> { ll n; ci(const ll n) : n(n) { } bool operator==(const ci& x) { return n == x.n; } bool operator!=(const ci& x) { return !(*this == x); } ci &operator++() { n++; return *this; } ll operator*() const { return n; } };

size_t random_seed; namespace std { using argument_type = P; template<> struct hash<argument_type> { size_t operator()(argument_type const& x) const { size_t seed = random_seed; seed ^= hash<ll>{}(x.fi); seed ^= (hash<ll>{}(x.se) << 1); return seed; } }; }; // hash for various class
namespace myhash{ const int Bsizes[]={3,9,13,17,21,25,29,33,37,41,45,49,53,57,61,65,69,73,77,81}; const int xor_nums[]={0x100007d1,0x5ff049c9,0x14560859,0x07087fef,0x3e277d49,0x4dba1f17,0x709c5988,0x05904258,0x1aa71872,0x238819b3,0x7b002bb7,0x1cf91302,0x0012290a,0x1083576b,0x76473e49,0x3d86295b,0x20536814,0x08634f4d,0x115405e8,0x0e6359f2}; const int hash_key=xor_nums[rand()%20]; const int mod_key=xor_nums[rand()%20]; template <typename T> struct myhash{ std::size_t operator()(const T& val) const { return (hash<T>{}(val)%mod_key)^hash_key; } }; };
template <typename T> class uset:public std::unordered_set<T,myhash::myhash<T>> { using SET=std::unordered_set<T,myhash::myhash<T>>; public: uset():SET(){SET::rehash(myhash::Bsizes[rand()%20]);} };
template <typename T,typename U> class umap:public std::unordered_map<T,U,myhash::myhash<T>> { public: using MAP=std::unordered_map<T,U,myhash::myhash<T>>; umap():MAP(){MAP::rehash(myhash::Bsizes[rand()%20]);} };    

struct timeval start; double sec() { struct timeval tv; gettimeofday(&tv, NULL); return (tv.tv_sec - start.tv_sec) + (tv.tv_usec - start.tv_usec) * 1e-6; }
struct init_{init_(){ gettimeofday(&start, NULL); ios::sync_with_stdio(false); cin.tie(0); srand((unsigned int)time(NULL)); random_seed = RAND_MAX / 2 + rand() / 2; }} init__;

static const double EPS = 1e-14;
static const long long INF = 1e18;
static const long long mo = 1e9+7;
#define ldout fixed << setprecision(40) 

// データ型T, 単位元T0, 可換二項演算子opが与えられた時、
//
// 点更新opをO(log n)、0-indexの範囲sum(int j)をO(log n)で実現
// もしopに逆演算が定義できるならば、i-indexの範囲sum(int i, int j)が実現可能。

// 0-indexed, sumは閉区間なので注意！！

void printBit(int a) {cout << a << " "; for(; a > 0; a >>= 1) cout << (a & 1); cout << "#bit" << endl;}
template <class T>
struct fenwick_tree {
    /**********************/
    // 実装箇所
    /**********************/
    T T0 = 0;
    T op(T a, T b) { return a + b; }
    /**********************/
    // 実装終わり
    /**********************/

    // xのデータ構造。op=+, invop=1, T=int, T0=0の場合
    // iが最右添字な数字列をs[i]として、x[i] = s[i]の総和 (例: i=5, s[i]="45", x[i]=9)
    // 0123456789ABCDEF
    // 01234567--------
    // 0123----89AB----
    // 01--23--89--CD--
    // 0-2-4-6-8-A-C-E-
    int n_org;
    vector<T> x;
    fenwick_tree(int n_)  { 
        n_org = n_;
        int n = 1; while (n <= n_) n *= 2;
        x = vector<T>(n, T0);
    }

    // 範囲クエリ: [0, j]のreduceを行う。閉区間に注意
    // O(log n)
    T query(int j) {
        T S = T0;
        for (j; j >= 0; j = (j & (j + 1)) - 1)  // jは、C->B->7と遷移する。0からCをカバーするための数字列の添字へ飛ぶ
            S = op(S, x[j]); 
        return S;
    }

    // 更新クエリ: #kにaを演算する
    // O(log n)
    void update(int k, T a) {
        for (; k < x.size(); k |= k+1) // kは、C->D->Fと遷移する。Cをカバーする数字列全てに飛ぶ
            x[k] = op(x[k], a); 
    }

    // #kにアクセスする
    // O(log n)
    T access(int k) {
        return query(k) - (k ? query(k-1) : 0);
    }
    void print(void) {
        for (int i = 0; i < n_org; i++) 
            cout << access(i) << " ";
        cout << endl;
    }
    void print_raw(void) {
        for (int i = 0; i < x.size(); i++) 
            cout << x[i] << " ";
        cout << endl;
    }
};

// 数列aの中で、全ての(i, j)ペア（ただしi<j）のうち、
// a[i] <= a[j]なる個数を数え上げる
//
// moで割った余りを出力するので注意！
//
// O(n log n)
ll countLR(vll a) {
    ll n = a.size();
    vector<P> ai(n);
    rep(i, n) {
        ai[i] = P(a[i], i);
    }
    sort(all(ai));

    fenwick_tree<ll> c(n);
    ll ret = 0;
    rep(i, n) {
        (ret += c.query(ai[i].se-1)) %= mo;
        c.update(ai[i].se, 1);
    }

    return ret;
}

int main(void) {
    ll n, k; cin >> n >> k;
    vll a(n); cin >> a;

    vll as(n+1);
    rep(i, n) as[i+1] = as[i] + a[i];
//    cout << as << endl;

    vll b(n+1);
    rep(i, n+1) {
        b[i] = as[i] - k * i;
    }
//    cout << b << endl;

    cout << countLR(b) << endl;

    return 0;
}


Compiler output:
main.c:1:10: fatal error: bits/stdc++.h: No such file or directory
    1 | #include <bits/stdc++.h>
      |          ^~~~~~~~~~~~~~~
compilation terminated.