Problem p02696 (C++)

Buggy submission (status: Time Limit Exceeded):
//----AUTHOR:kkdrummer----/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long ll;
typedef long double ld;
// typedef    unordered_set<ll>   usll;
// typedef    unordered_multiset<ll>   umsll;
typedef multiset<ll> msll;
typedef set<ll> sll;
typedef vector<ll> vll;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
typedef priority_queue<ll> pqll;
typedef vector<int> vi;
typedef set<int> si;
typedef multiset<int> msi;
// typedef    unordered_multiset<int>   umsi;
// typedef    unordered_set<int>   usi;
typedef pair<int, int> pi;
typedef vector<pi> vpi;
typedef set<pi> spi;
typedef priority_queue<int> pqi;
typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ind_set;
typedef tree<ll, null_type, less<ll>, rb_tree_tag,
             tree_order_statistics_node_update>
    ind_setll;
#define in insert
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define be begin
#define en end
#define itr iterator
#define io                                                                     \
  ios_base::sync_with_stdio(false);                                            \
  cin.tie(NULL);                                                               \
  cout.tie(NULL);
#define mo 1000000007
#define inf 9223372036854775807
#define ninf -inf
#define ima 2147483647
#define imi -ima
#define oncnt __builtin_popcount
#define zerobegin __builtin_clz
#define zeroend __builtin_ctz
#define parity __builtin_parity
#define all(x) x.be(), x.en()
#define eps 1e-9
#define coutd cout << setprecision(10) << fixed
#define mems(dp, x) memset(dp, x, sizeof(dp))
const ld PI = 3.1415926535897932384626433832792884197169399375105820974944;
inline ll modpow(ll x, ll n) {
  if (n == 0)
    return 1;
  if (n == 1)
    return (x % mo);
  ll u = (modpow(x, n / 2));
  u = (u * u) % mo;
  if (n % 2 != 0)
    u = (u * x % mo) % mo;
  return u;
}
inline ll modinv(ll x) { return modpow(x, mo - 2); }
inline ll mmul(ll a, ll b) {
  if (a >= mo)
    a = a % mo;
  if (b >= mo)
    b = b % mo;
  if (a * b >= mo)
    return (a * b) % mo;
  return (a * b);
}
inline ll madd(ll a, ll b) {
  if (a >= mo)
    a = a % mo;
  if (b >= mo)
    b = b % mo;
  if (a + b >= mo)
    return (a + b) % mo;
  return (a + b);
}
inline ll msub(ll a, ll b) {
  if (a >= mo)
    a = a % mo;
  if (b >= mo)
    b = b % mo;
  return (((a - b) % mo + mo) % mo);
}
inline ll mdiv(ll a, ll bb) {
  if (a >= mo)
    a = a % mo;
  ll b = modinv(bb);
  if (b >= mo)
    b = b % mo;
  if (a * b >= mo)
    return (a * b) % mo;
  return (a * b);
}
inline ll gcd(ll a, ll b) { return __gcd(a, b); }
inline ll lcm(ll a, ll b) { return ((a * b) / gcd(a, b)); }

ll val(ll a, ll b, ll x) { return ((a * x) / b) - (a * (x / b)); }

int main() {
  io int testcases = 1; // cin>>testcases;
  while (testcases--) {

    ll a, b, n;
    cin >> a >> b >> n;

    ll am = 0;
    if (n < b)
      cout << val(a, b, n);

    else if ((n / b) < 10000000) {

      for (ll i = b - 1; i <= n; i += b) {
        ll vp = val(a, b, i);
        if (am > vp)
          break;
        am = max(am, vp);
      }
      am = max(val(a, b, n), am);
      cout << am;
    }

    else {
      for (ll i = n - (n % b) - 1; i >= 1; i -= b) {
        ll vp = val(a, b, i);
        if (am > vp)
          break;
        am = max(am, vp);
      }
      am = max(val(a, b, n), am);
      cout << am;
    }
  }
  return 0;
}


Fixed submission:
//----AUTHOR:kkdrummer----/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long ll;
typedef long double ld;
// typedef    unordered_set<ll>   usll;
// typedef    unordered_multiset<ll>   umsll;
typedef multiset<ll> msll;
typedef set<ll> sll;
typedef vector<ll> vll;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
typedef priority_queue<ll> pqll;
typedef vector<int> vi;
typedef set<int> si;
typedef multiset<int> msi;
// typedef    unordered_multiset<int>   umsi;
// typedef    unordered_set<int>   usi;
typedef pair<int, int> pi;
typedef vector<pi> vpi;
typedef set<pi> spi;
typedef priority_queue<int> pqi;
typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ind_set;
typedef tree<ll, null_type, less<ll>, rb_tree_tag,
             tree_order_statistics_node_update>
    ind_setll;
#define in insert
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define be begin
#define en end
#define itr iterator
#define io                                                                     \
  ios_base::sync_with_stdio(false);                                            \
  cin.tie(NULL);                                                               \
  cout.tie(NULL);
#define mo 1000000007
#define inf 9223372036854775807
#define ninf -inf
#define ima 2147483647
#define imi -ima
#define oncnt __builtin_popcount
#define zerobegin __builtin_clz
#define zeroend __builtin_ctz
#define parity __builtin_parity
#define all(x) x.be(), x.en()
#define eps 1e-9
#define coutd cout << setprecision(10) << fixed
#define mems(dp, x) memset(dp, x, sizeof(dp))
const ld PI = 3.1415926535897932384626433832792884197169399375105820974944;
inline ll modpow(ll x, ll n) {
  if (n == 0)
    return 1;
  if (n == 1)
    return (x % mo);
  ll u = (modpow(x, n / 2));
  u = (u * u) % mo;
  if (n % 2 != 0)
    u = (u * x % mo) % mo;
  return u;
}
inline ll modinv(ll x) { return modpow(x, mo - 2); }
inline ll mmul(ll a, ll b) {
  if (a >= mo)
    a = a % mo;
  if (b >= mo)
    b = b % mo;
  if (a * b >= mo)
    return (a * b) % mo;
  return (a * b);
}
inline ll madd(ll a, ll b) {
  if (a >= mo)
    a = a % mo;
  if (b >= mo)
    b = b % mo;
  if (a + b >= mo)
    return (a + b) % mo;
  return (a + b);
}
inline ll msub(ll a, ll b) {
  if (a >= mo)
    a = a % mo;
  if (b >= mo)
    b = b % mo;
  return (((a - b) % mo + mo) % mo);
}
inline ll mdiv(ll a, ll bb) {
  if (a >= mo)
    a = a % mo;
  ll b = modinv(bb);
  if (b >= mo)
    b = b % mo;
  if (a * b >= mo)
    return (a * b) % mo;
  return (a * b);
}
inline ll gcd(ll a, ll b) { return __gcd(a, b); }
inline ll lcm(ll a, ll b) { return ((a * b) / gcd(a, b)); }

ll val(ll a, ll b, ll x) { return ((a * x) / b) - (a * (x / b)); }

int main() {
  io int testcases = 1; // cin>>testcases;
  while (testcases--) {

    ll a, b, n;
    cin >> a >> b >> n;

    ll am = 0;
    if (n < b)
      cout << val(a, b, n);

    else if ((n / b) < 10000000) {

      for (ll i = b - 1; i <= n; i += b) {
        ll vp = val(a, b, i);
        if (am > vp)
          break;
        am = max(am, vp);
      }
      am = max(val(a, b, n), am);
      cout << am;
    }

    else {
      cout << val(a, b, n);
    }
  }
  return 0;
}