Problem p03966 (C++)

Buggy submission (status: Time Limit Exceeded):

#include <algorithm>
#include <cmath>
#include <complex> // complex<double> a(1.2 , 2.3);// real(): 1.2, imag()2.3
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <vector>
using namespace std;

#define MOD 1000000007
#define ll long long
#define ld long double
#define FOR(i, a, b) for (ll i = (ll)a; i < (ll)b; i++)
#define rep(i, n) FOR(i, 0, n)
#define pb push_back
#define mp make_pair
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define rmsame(a) sort(all(a)), a.erase(unique(all(a)), a.end())
#define rmvector(a, b)                                                         \
  rep(i, a.size()) rep(j, b.size()) if (a[i] == b[j]) {                        \
    a.erase(a.begin() + i);                                                    \
    i--;                                                                       \
    break;                                                                     \
  }
template <typename X> bool exist(vector<X> vec, X item) {
  return find(all(vec), item) != vec.end();
}
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

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

  ll N;
  cin >> N;

  ll a = 0, b = 0;

  rep(i, N) {
    ll x, y;
    cin >> x >> y;

    for (ll j = 0;; j++) {
      if (j == 0)
        continue;
      if (((x * j) >= a) && ((y * j) >= b)) {
        a = x * j;
        b = y * j;
        break;
      }
    }
  }
  cout << a + b << endl;

  // cout << fixed << setprecision(16) << ans << endl;
  return 0;
}


Fixed submission:

#include <algorithm>
#include <cmath>
#include <complex> // complex<double> a(1.2 , 2.3);// real(): 1.2, imag()2.3
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <vector>
using namespace std;

#define MOD 1000000007
#define ll long long
#define ld long double
#define FOR(i, a, b) for (ll i = (ll)a; i < (ll)b; i++)
#define rep(i, n) FOR(i, 0, n)
#define pb push_back
#define mp make_pair
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define rmsame(a) sort(all(a)), a.erase(unique(all(a)), a.end())
#define rmvector(a, b)                                                         \
  rep(i, a.size()) rep(j, b.size()) if (a[i] == b[j]) {                        \
    a.erase(a.begin() + i);                                                    \
    i--;                                                                       \
    break;                                                                     \
  }
template <typename X> bool exist(vector<X> vec, X item) {
  return find(all(vec), item) != vec.end();
}
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

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

  ll N;
  cin >> N;

  ll a = 0, b = 0;

  rep(i, N) {
    ll x, y;
    cin >> x >> y;

    for (ll j = max(a / x, b / y);; j++) {
      if (j == 0)
        continue;
      if (((x * j) >= a) && ((y * j) >= b)) {
        a = x * j;
        b = y * j;
        break;
      }
    }
  }
  cout << a + b << endl;

  // cout << fixed << setprecision(16) << ans << endl;
  return 0;
}