제출 #75441

#제출 시각아이디문제언어결과실행 시간메모리
75441WLZVudu (COCI15_vudu)C++17
42 / 140
1087 ms66560 KiB
#include <iostream>
#include <vector>
#include <algorithm>
#include <map>

using namespace std;

template<typename T>
class fenwick {
  private:
    int n;
    vector<int> fenw;
  public:

    fenwick(int _n) : n(_n) {
      fenw.resize(n);
    }

    void modify(int x, T v) {
      while (x < n) {
        fenw[x] += v;
        x |= (x + 1);
      }
    }

    T get(int x) {
      T v{};
      while (x >= 0) {
        v += fenw[x];
        x = (x & (x + 1)) - 1;
      }
      return v;
    }
};

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  vector<int> a(n);
  vector<int> b(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  int p;
  cin >> p;
  for (int i = 0; i < n; i++) {
    a[i] -= p;
  }
  b[0] = a[0];
  for (int i = 1; i < n; i++) {
    a[i] += a[i - 1];
    b[i] = a[i];
  } 
  sort(b.begin(), b.end());
  map<int, int> mp;
  for (int i = 0; i < n; i++) {
    mp[a[i]] = lower_bound(b.begin(), b.end(), a[i]) - b.begin();
  }
  fenwick<int> fenw(n);
  long long ans = 0ll;
  for (int i = 0; i < n; i++) {
    if (a[i] >= 0) {
      ans++;
    }
    ans += (long long) (fenw.get(mp[a[i]]));
    fenw.modify(mp[a[i]], +1);
  }
  cout << ans << endl;
  return 0;
}
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