Problem p02696 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <vector>
#define _USE_MATH_DEFINES
#include <cassert>
#include <cctype>
#include <cfloat>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
using namespace std;

#define EPS 1e-12
#define ull unsigned long long
#define ll long long
#define VI vector<ll>
#define PII pair<ll, ll>
#define VVI vector<vector<ll>>
#define VVVI vector<vector<vector<ll>>>
#define VVVVI vector<vector<vector<vector<ll>>>>
#define REP(i, n) for (ll i = 0, _n = (n); (i) < (ll)_n; ++i)
#define REPR(i, n) for (ll i = (ll)(n)-1; 0 <= (i); --i)
#define RANGE(i, a, b) for (ll i = (ll)a, _b = (ll)(b); (i) < _b; ++i)
#define RANGER(i, a, b) for (ll i = (ll)(b)-1, _a = (ll)(a); (_a) <= i; --i)
#define FOR(i, c)                                                              \\
  for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define ALLR(c) (c).rbegin(), (c).rend()
#define PB push_back
#define MP(a, b) make_pair(a, b)
#define POPCOUNT __builtin_popcount
#define POPCOUNTLL __builtin_popcountll
#define CLEAR(table, v) memset(table, v, sizeof(table));
#define UNIFORM_DOUBLE(a, b)                                                   \\
  (((b - a) * (double)rand() / RAND_MAX) + a)      // [a, b)
#define UNIFORM_LL(a, b) (ll) UNIFORM_DOUBLE(a, b) // [a, b)
#define IN(v, lo, hi) ((lo) <= (v) && (v) < (hi))
#define DD(v) cout << #v << ": " << v << endl
#define FI first
#define SE second
template <typename T0, typename T1>
std::ostream &operator<<(std::ostream &os, const map<T0, T1> &v) {
  for (typename map<T0, T1>::const_iterator p = v.begin(); p != v.end(); p++) {
    os << p->first << ": " << p->second << " ";
  }
  return os;
}
template <typename T0, typename T1>
std::ostream &operator<<(std::ostream &os, const pair<T0, T1> &v) {
  os << v.first << ": " << v.second << " ";
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const vector<T> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << " ";
  }
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const set<T> &v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const deque<T> &v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const vector<vector<T>> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << endl;
  }
  return os;
}
template <typename T> void maxUpdate(T &a, T b) { a = max(a, b); }
template <typename T> void minUpdate(T &a, T b) { a = min(a, b); }
string YN(bool v) { return v ? "Yes" : "No"; }
void uniq(VI &es) {
  sort(ALL(es));
  es.erase(unique(ALL(es)), es.end());
}

#define INF (1LL << 60)
/*
x=Byで0
x=[0, B-1]では単消費減少, これを繰り返す
*/
ll f(ll A, ll B, ll N) {
  auto g = [&](ll x) { return A * x / B - A * (x / B); };
  //	VI vs(N+1);
  //	REP(x, N+1) vs[x]=g(x);
  //	ll ref=*max_element(ALL(vs));
  ll ans = g(min(N, B - 1));

  //	if(ref!=ans) {
  //		DD(A);DD(B);DD(N);
  //		DD(ref);
  //		DD(ans);
  //		DD(vs);
  //	}
  return ans;
}

int main() {
  //	RANGE(A, 1, 10000) RANGE(B, 1, 10000) RANGE(N, 100, 101) {
  //		f(A, B, N);
  //	}
  //	return 0;

  cin.tie(0);
  ios::sync_with_stdio(false);
  ll A, B, N;
  while (cin >> A >> B >> N) {
    ll ans = f(A, B, N);
    cout << ans << endl;
  }

  return 0;
}


Error: 0

Fixed submission:

#include <algorithm>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <vector>
#define _USE_MATH_DEFINES
#include <cassert>
#include <cctype>
#include <cfloat>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
using namespace std;

#define EPS 1e-12
#define ull unsigned long long
#define ll long long
#define VI vector<ll>
#define PII pair<ll, ll>
#define VVI vector<vector<ll>>
#define VVVI vector<vector<vector<ll>>>
#define VVVVI vector<vector<vector<vector<ll>>>>
#define REP(i, n) for (ll i = 0, _n = (n); (i) < (ll)_n; ++i)
#define REPR(i, n) for (ll i = (ll)(n)-1; 0 <= (i); --i)
#define RANGE(i, a, b) for (ll i = (ll)a, _b = (ll)(b); (i) < _b; ++i)
#define RANGER(i, a, b) for (ll i = (ll)(b)-1, _a = (ll)(a); (_a) <= i; --i)
#define FOR(i, c)                                                              \\
  for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define ALLR(c) (c).rbegin(), (c).rend()
#define PB push_back
#define MP(a, b) make_pair(a, b)
#define POPCOUNT __builtin_popcount
#define POPCOUNTLL __builtin_popcountll
#define CLEAR(table, v) memset(table, v, sizeof(table));
#define UNIFORM_DOUBLE(a, b)                                                   \\
  (((b - a) * (double)rand() / RAND_MAX) + a)      // [a, b)
#define UNIFORM_LL(a, b) (ll) UNIFORM_DOUBLE(a, b) // [a, b)
#define IN(v, lo, hi) ((lo) <= (v) && (v) < (hi))
#define DD(v) cout << #v << ": " << v << endl
#define FI first
#define SE second
template <typename T0, typename T1>
std::ostream &operator<<(std::ostream &os, const map<T0, T1> &v) {
  for (typename map<T0, T1>::const_iterator p = v.begin(); p != v.end(); p++) {
    os << p->first << ": " << p->second << " ";
  }
  return os;
}
template <typename T0, typename T1>
std::ostream &operator<<(std::ostream &os, const pair<T0, T1> &v) {
  os << v.first << ": " << v.second << " ";
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const vector<T> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << " ";
  }
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const set<T> &v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const deque<T> &v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const vector<vector<T>> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << endl;
  }
  return os;
}
template <typename T> void maxUpdate(T &a, T b) { a = max(a, b); }
template <typename T> void minUpdate(T &a, T b) { a = min(a, b); }
string YN(bool v) { return v ? "Yes" : "No"; }
void uniq(VI &es) {
  sort(ALL(es));
  es.erase(unique(ALL(es)), es.end());
}

#define INF (1LL << 60)
/*
x=Byで0
x=[0, B-1]では単消費減少, これを繰り返す
*/
ll f(ll A, ll B, ll N) {
  auto g = [&](ll x) { return A * x / B - A * (x / B); };
  VI vs(N + 1);
  REP(x, N + 1) vs[x] = g(x);
  ll ref = *max_element(ALL(vs));
  ll ans = g(min(N, B - 1));

  if (ref != ans) {
    DD(A);
    DD(B);
    DD(N);
    DD(ref);
    DD(ans);
    DD(vs);
  }
  return ans;
}

int main() {
  //	RANGE(A, 1, 10000) RANGE(B, 1, 10000) RANGE(N, 100, 101) {
  //		f(A, B, N);
  //	}
  //	return 0;

  cin.tie(0);
  ios::sync_with_stdio(false);
  ll A, B, N;
  while (cin >> A >> B >> N) {
    ll ans = f(A, B, N);
    cout << ans << endl;
  }

  return 0;
}