Submission #1690825

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Source Code Expand

#include <bits/stdc++.h>
 
#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)
 
#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=(int)(a)-1;i>=(int)(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)
 
#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
 
// #define DEBUG
 
#ifdef DEBUG
    #define dump(...) fprintf(stderr, __VA_ARGS__)
#else
    #define dump(...)
#endif
 
template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}
 
using namespace std;
using ll=long long;
using vi=vector<int>;
using vll=vector<ll>;
 
const double EPS = 1e-10;
const double PI = acos(-1.0);
const ll inf =1LL << 62;
const ll mod=1000000007LL;
const int dx[4]={1,0,-1,0};
const int dy[4]={0,1,0,-1};
 
 
ll extgcd(ll a,ll b,ll& x,ll& y){x=1,y=0;ll g=a;if(b!=0) g=extgcd(b,a%b,y,x),y-=a/b*x;return g;}
ll ADD(const ll &a, const ll &b,const ll &mod) { return (a+b)%mod;}
ll SUB(const ll &a, const ll &b,const ll &mod) { return (a-b+mod)%mod;}
ll MUL(const ll &a, const ll &b,const ll &mod) { return (1LL*a*b)%mod;}
ll DIV(const ll &a, const ll &b,const ll &mod) {ll x,y; extgcd(b,mod,x,y);return MUL(a,(x+mod)%mod,mod);}
 
random_device rd;
mt19937 mt(rd());
uniform_int_distribution<int> dice(1,6);
uniform_real_distribution<double> score(0.0,10.0);

template <typename T>
class Bit {
 public:
  Bit(int size) : size_(size) {
    data_.resize(size + 1);
  }

  // 0-indexed
  void add(int index, T value) {
    if (index < 0 || index >= size_) return;
    ++index;
    while (index <= size_) {
      data_[index] += value;
      index += index & -index;
    }
  }

  // [0, index]
  T sum(int index) {
    if (index < 0 || index >= size_) return 0;
    ++index;
    T ret = 0;
    while (index > 0) {
      ret += data_[index];
      index -= index & -index;
    }
    return ret;
  }

 private:
  std::vector<T> data_;
  int size_;
};

void compress(vll const& vec, map<ll, int>& zip, vll& unzip){
    unzip = vec;

    sort(_all(unzip));
    unzip.erase(unique(_all(unzip)), unzip.end());
    unzip.emplace_back(inf);

    rep(i, unzip.size()) zip[unzip[i]] = i;
}

int main(void){
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n; ll K; cin >> n >> K;
    vll a(n); for(auto& e : a) cin >> e;
    a.emplace_back(0);
    n++;
    ll sum = 0;
    rep(i, n){
        ll cur = a[i];
        a[i] = sum - i * K;
        sum += cur;
    }

    map<ll, int> zip; vll unzip;
    compress(a, zip, unzip);
    rep(i, n) a[i] = zip[a[i]];

    Bit<int> bt(n);
    ll res = 0;
    rep(i, n){
        res += bt.sum(a[i]);
        bt.add(a[i], 1);
    }

    cout << res << endl;

    return 0;
}

Submission Info

Judge Result