Problem p02696 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef long double ld;

typedef set<int>::iterator sit;
typedef map<int, int>::iterator mit;
typedef vector<int>::iterator vit;

const int INF = 1e9 + 7;
const int MOD = 1e9 + 7;
const int MAXN = 1e6 + 3;

#define _ % MOD
#define __ %= MOD

#define each(it, s) for (auto it = s.begin(); it != s.end(); ++it)
#define sortA(v) sort(v.begin(), v.end())
#define sortD(v) sort(v.begin(), v.end(), greater<auto>())
#define fill(a) memset(a, 0, sizeof(a))

#define swap(a, b)                                                             \
  {                                                                            \
    a = a + b;                                                                 \
    b = a - b;                                                                 \
    a = a - b;                                                                 \
  }
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define repA(i, a, n) for (ll i = a; i <= (n); ++i)
#define repD(i, a, n) for (ll i = a; i >= (n); --i)
#define watch(x) cout << (#x) << " is " << (x) << endl

#define fi first
#define se second
#define mp make_pair
#define pb push_back

#define fbo find_by_order
#define ook order_of_key

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
ll power(ll x, ll y) {
  ll res = 1;
  while (y > 0) {
    if (y & 1)
      res = res * x;
    y = y >> 1;
    x = x * x;
  }
  return res;
} // modular exponent

int main() {
  ios_base::sync_with_stdio(false); // don't use printf and scanf
  cin.tie(NULL);                    // cout<<fixed<<setprecision
  ll a, b, n;
  cin >> a >> b >> n;
  ll q = n / b;
  // ll rem=n%b;
  ll ans = 0;
  ans = max(ans, (a * n) / b - a * (n / b));
  repA(i, 1, q) { ans = max(ans, (a * ((ll)i * b - 1)) / b - a * ((ll)i - 1)); }
  cout << ans << '\n';
  return 0;
}
// JUST ASK YOURSELF DID YOU GIVE YOUR BEST ? ISSE ZYADA
// KUCH KAR BHI NAHI SAKTE !! ENJOY AND GIVE YOUR BEST!!


Fixed submission:
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef long double ld;

typedef set<int>::iterator sit;
typedef map<int, int>::iterator mit;
typedef vector<int>::iterator vit;

const int INF = 1e9 + 7;
const int MOD = 1e9 + 7;
const int MAXN = 1e6 + 3;

#define _ % MOD
#define __ %= MOD

#define each(it, s) for (auto it = s.begin(); it != s.end(); ++it)
#define sortA(v) sort(v.begin(), v.end())
#define sortD(v) sort(v.begin(), v.end(), greater<auto>())
#define fill(a) memset(a, 0, sizeof(a))

#define swap(a, b)                                                             \
  {                                                                            \
    a = a + b;                                                                 \
    b = a - b;                                                                 \
    a = a - b;                                                                 \
  }
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define repA(i, a, n) for (ll i = a; i <= (n); ++i)
#define repD(i, a, n) for (ll i = a; i >= (n); --i)
#define watch(x) cout << (#x) << " is " << (x) << endl

#define fi first
#define se second
#define mp make_pair
#define pb push_back

#define fbo find_by_order
#define ook order_of_key

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
ll power(ll x, ll y) {
  ll res = 1;
  while (y > 0) {
    if (y & 1)
      res = res * x;
    y = y >> 1;
    x = x * x;
  }
  return res;
} // modular exponent

int main() {
  ios_base::sync_with_stdio(false); // don't use printf and scanf
  cin.tie(NULL);                    // cout<<fixed<<setprecision
  ll a, b, n;
  cin >> a >> b >> n;
  ll x = min(b - 1, n);
  ll ans = (a * x) / b - a * (x / b);
  cout << ans << '\n';
  return 0;
}
// JUST ASK YOURSELF DID YOU GIVE YOUR BEST ? ISSE ZYADA
// KUCH KAR BHI NAHI SAKTE !! ENJOY AND GIVE YOUR BEST!!