Binge watching

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>

using namespace std;

const int N = 4e5 + 5;

struct fenwick_tree {
  int f[N];

  fenwick_tree() {
    memset(f, 0, sizeof(f));
  }

  void upd(int i, int x) {
    for (; i < N; i += i & -i) {
      f[i] = max(f[i], x);
    }
  }

  int get(int i) {
    int r = 0;
    for (; i > 0; i -= i & -i) {
      r = max(r, f[i]);
    }
    return r;
  }
};

int n;
pair<int, int> p[N];
vector<int> v;
fenwick_tree ft;
 
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> p[i].first >> p[i].second;
    v.emplace_back(p[i].first);
    v.emplace_back(p[i].second);
  }
  sort(p + 1, p + n + 1);
  sort(v.begin(), v.end());
  v.erase(unique(v.begin(), v.end()), v.end());
  for (int i = 1; i <= n; i++) {
    p[i].first = lower_bound(v.begin(), v.end(), p[i].first) - v.begin() + 1;
    p[i].second = lower_bound(v.begin(), v.end(), p[i].second) - v.begin() + 1;
    ft.upd(p[i].second, 1 + ft.get(p[i].first));
  }
  cout << ft.get(N - 1);
  return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED