Problem p02696 (C++) — buggy submission, verdict: Time Limit Exceeded

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

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update

using namespace __gnu_pbds;
using namespace std;

#define sz(a) int((a).size())
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(), (c).end()
#define tr(c, i)                                                               \\
  for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); i++)
#define present(c, x) ((c).find(x) != (c).end())
#define cpresent(c, x) (find(all(c), x) != (c).end())
#define minei(x) min_element(x.begin(), x.end()) - (x).begin()
#define maxei(x) max_element(x.begin(), x.end()) - (x).begin()
#define LSOne(S) (S & (-S))

#define uns(v)                                                                 \\
  sort((v).begin(), (v).end()), v.erase(unique(v.begin(), v.end()), v.end())
#define acusum(x) accumulate(x.begin(), x.end(), 0)
#define acumul(x) accumulate(x.begin(), x.end(), 1, multiplies<int>());
#define bits(x) __builtin_popcount(x)
#define oo INT_MAX
#define inf 1000000000000000000ll
const long long MAXN = 1e7;
#define MOD 1000000007

const double pi = acos(-1.0);
const double eps = 1e-11;

typedef long long ll;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<int> vi;
typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    indexed_set;

int main() {
  std::ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ll A, B, N;
  cin >> A >> B >> N;
  cout << A * min(B - 1, N) / B << endl;
  return 0;
}

Error: TLE

Fixed submission:

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

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update

using namespace __gnu_pbds;
using namespace std;

#define sz(a) int((a).size())
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(), (c).end()
#define tr(c, i)                                                               \\
  for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); i++)
#define present(c, x) ((c).find(x) != (c).end())
#define cpresent(c, x) (find(all(c), x) != (c).end())
#define minei(x) min_element(x.begin(), x.end()) - (x).begin()
#define maxei(x) max_element(x.begin(), x.end()) - (x).begin()
#define LSOne(S) (S & (-S))

#define uns(v)                                                                 \\
  sort((v).begin(), (v).end()), v.erase(unique(v.begin(), v.end()), v.end())
#define acusum(x) accumulate(x.begin(), x.end(), 0)
#define acumul(x) accumulate(x.begin(), x.end(), 1, multiplies<int>());
#define bits(x) __builtin_popcount(x)
#define oo INT_MAX
#define inf 1000000000
const long long MAXN = 1e8;
#define MOD 1000000007

const double pi = acos(-1.0);
const double eps = 1e-11;

typedef long long ll;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<int> vi;
typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    indexed_set;

int main() {
  std::ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ll A, B, N;
  cin >> A >> B >> N;
  ll mx = 0;
  ll res;
  for (ll x = 0; x <= min(MAXN, N); x++) {
    res = floor(A * x / B) - A * floor(x / B);
    mx = max(mx, res);
  }
  for (ll x = N; x >= max(0ll, N - MAXN); x--) {
    res = floor(A * x / B) - A * floor(x / B);
    mx = max(mx, res);
  }
  cout << mx << endl;
  return 0;
}