Binge watching

input/code.cpp: In function 'int chain_movies(vpi&, vpi)':
input/code.cpp:40:15: warning: variable 'm' set but not used [-Wunused-but-set-variable]
   40 |     for (auto m : chain) {
      |               ^
input/code.cpp: In function 'int main()':
input/code.cpp:82:13: warning: variable 'm' set but not used [-Wunused-but-set-variable]
   82 |   for (auto m : chain) {
      |             ^

// #include <bits/stdc++.h>
#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 0

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

int chain_movies(vpi &all_movies, vpi chain) {
  bool nomore = true;
  int max = 0;

  for (auto m : all_movies) {
    if (chain.empty() || (m.F >= chain.back().S)) {
      nomore = false;
      vpi nc = chain;
      nc.push_back(m);
      int chain_len = chain_movies(all_movies, nc);
      if (chain_len > max) {
        max = chain_len;
      }
    }
  }
  if (nomore) {
    DBG("NEW CHAIN:")
    for (auto m : chain) {
      DBG("start: " << m.F << ", end: " << m.S)
    }
    DBG("size: " << chain.size() << "\n")
    return chain.size();
  } else {
    return max;
  }
}

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

    for (auto m : movies) {
      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

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: TIME LIMIT EXCEEDED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED