Problem p03700 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
#include <cmath>
#include <iostream>
#include <string>
#include <unordered_map>
#include <unordered_set>
using namespace std;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define FORR(i, a, b) for (ll i = (a); i <= (b); i++)
#define repR(i, n) for (ll i = n; i >= 0; i--)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define F first
#define S second
#define pb push_back
#define pu push
#define COUT(x) cout << (x) << endl
#define PQ priority_queue<ll>
#define PQR priority_queue<ll, vector<ll>, greater<ll>>
#define YES(n) cout << ((n) ? "YES" : "NO") << endl
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl
#define mp make_pair
#define maxs(x, y) (x = max(x, y))
#define mins(x, y) (x = min(x, y))
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const ll MOD = 1000000007LL;
const ll INF = 1LL << 60;
using vll = vector<ll>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvll = vector<vll>;
using vstr = vector<string>;
using pll = pair<ll, ll>;
using vc = vector<char>;
using vvc = vector<vc>;
ll dx[4] = {0, 1, 0, -1};
ll dy[4] = {1, 0, -1, 0};
int main() {
  ll n, a, b;
  cin >> n >> a >> b;
  vll h(n);
  rep(i, n) cin >> h[i];
  ll l = 0;
  ll r = 1e9;
  ll mid = (l + r) / 2;
  while (l < r) {
    ll cu = 0;
    rep(i, n) {
      if (h[i] - b * mid > 0) {
        cu += (h[i] - b * mid + a - 1 - b) / (a - b);
      }
    }
    if (cu <= mid) {
      r = mid;
    } else
      l = mid;
    mid = (l + r) / 2;
  }
  COUT(r);
}


Fixed submission:
#include <bits/stdc++.h>
#include <cmath>
#include <iostream>
#include <string>
#include <unordered_map>
#include <unordered_set>
using namespace std;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define FORR(i, a, b) for (ll i = (a); i <= (b); i++)
#define repR(i, n) for (ll i = n; i >= 0; i--)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define F first
#define S second
#define pb push_back
#define pu push
#define COUT(x) cout << (x) << endl
#define PQ priority_queue<ll>
#define PQR priority_queue<ll, vector<ll>, greater<ll>>
#define YES(n) cout << ((n) ? "YES" : "NO") << endl
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl
#define mp make_pair
#define maxs(x, y) (x = max(x, y))
#define mins(x, y) (x = min(x, y))
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const ll MOD = 1000000007LL;
const ll INF = 1LL << 60;
using vll = vector<ll>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvll = vector<vll>;
using vstr = vector<string>;
using pll = pair<ll, ll>;
using vc = vector<char>;
using vvc = vector<vc>;
ll dx[4] = {0, 1, 0, -1};
ll dy[4] = {1, 0, -1, 0};
int main() {
  ll n, a, b;
  cin >> n >> a >> b;
  vll h(n);
  rep(i, n) cin >> h[i];
  ll l = 0;
  ll r = 1e9;
  ll mid = (l + r) / 2;
  while (l < r) {
    ll cu = 0;
    rep(i, n) {
      if (h[i] - b * mid > 0) {
        cu += (h[i] - b * mid + a - 1 - b) / (a - b);
      }
    }
    if (cu <= mid) {
      r = mid;
    } else
      l = mid + 1;
    mid = (l + r) / 2;
  }
  COUT(r);
}