Binge watching

// #include <bits/stdc++.h>
#include <algorithm>
#include <ios>
#include <iostream>
#include <vector>

// #include <iostream>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
typedef vector<pair<int, int>> vpi;
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define DO_DBG 1

#if DO_DBG
#define DBG(x) cerr << x << "\n";
#else
#define DBG(x)
#endif

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  DBG("INIT")
  int n;
  cin >> n;

  vpi movies;
  for (int i = 0; i < n; i++) {
    int start, end;
    cin >> start >> end;
    movies.PB(MP(start, end));
  }

  std::sort(movies.begin(), movies.end(),
            [](auto &left, auto &right) { return left.second < right.second; });

  vpi chain;
  while (1) {
    int earliest_end = 0;
    pi nxt = {};

    for (auto m : movies) {
      // we build the chain by continously picking the next movie by
      // finding a movie that
      // a) ends as early as possible
      // b) starts after the last movie in the current chain ends (or if the
      // chain is empty)
      if ((earliest_end == 0 || m.S < earliest_end) &&
          (chain.empty() || m.F >= chain.back().S)) {
        earliest_end = m.S;
        nxt = m;
      }
    }
    if (earliest_end == 0) {
      break;
    }
    chain.push_back(nxt);
  }

  DBG("NEW CHAIN:")
  for (auto m : chain) {
    DBG("start: " << m.F << ", end: " << m.S)
  }
  DBG("size: " << chain.size() << "\n")

  cout << chain.size() << "\n";
}

Test 1

Verdict: ACCEPTED

INIT
NEW CHAIN:
start: 1, end: 2
start: 2, end: 3
start: 3, end: 4
start: 4, end: 5
start:...

Test 2

Verdict: ACCEPTED

INIT
NEW CHAIN:
start: 1, end: 1000
size: 1

Test 3

Verdict: ACCEPTED

INIT
NEW CHAIN:
start: 201, end: 255
start: 457, end: 601
start: 699, end: 804
start: 832,...

Test 4

Verdict: TIME LIMIT EXCEEDED

Test 5

Verdict: ACCEPTED

INIT
NEW CHAIN:
start: 1, end: 1000000000
size: 1

Test 6

Verdict: ACCEPTED

INIT
NEW CHAIN:
start: 722928, end: 1399549
start: 3340526, end: 4902968
start: 6322519, e...

Test 7

Verdict: ACCEPTED

INIT
NEW CHAIN:
start: 2, end: 3
start: 5, end: 6
size: 2

Test 8

Verdict: ACCEPTED

INIT
NEW CHAIN:
start: 3, end: 4
start: 5, end: 6
start: 7, end: 8
size: 3

Test 9

Verdict: ACCEPTED

INIT
NEW CHAIN:
start: 1, end: 2
start: 3, end: 4
size: 2