Problem p02754 (C++)

Buggy submission (status: Runtime Error):
// Author - Sumit

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;

#pragma GCC optimize("O3")
#pragma GCC target("avx")

#define ll long long
#define int ll
#define ps push
#define pb emplace_back
#define INF 1LL << 60
#define MOD 1e9 + 7
#define mp make_pair
#define rep(i, a, b) for (int i = a; i < b; i++)
#define repd(i, a, b) for (int i = a; i >= b; i--)
#define all(v) v.begin(), v.end()
#define pii pair<int, int>
#define F first
#define S second
#define mii map<int, int>
#define vi vector<int>
#define vvi vector<vi>
#define vpii vector<pair<int, int>>
#define itr ::iterator it
#define WL(t) while (t--)
#define gcd(a, b) __gcd((a), (b))
#define lcm(a, b) ((a) * (b)) / gcd((a), (b))
#define lower(v, x) (lower_bound(all(v), x) - v.begin())
#define upper(v, x) (upper_bound(all(v), x) - v.begin())
#define debug(x) cout << x << "\n";
#define debug2(x, y) cout << x << " " << y << "\n";
#define debug3(x, y, z) cout << x << " " << y << " " << z << endl;

typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    pbds;

template <typename T, typename U> inline void remin(T &x, U y) {
  if (y < x)
    x = y;
}
template <typename T, typename U> inline void remax(T &x, U y) {
  if (x < y)
    x = y;
}
template <typename T> T pow(T a, T b, T m) {
  T ans = 1;
  while (b > 0) {
    if (b % 2 == 1)
      ans = (ans * a) % m;
    b /= 2;
    a = (a * a) % m;
  }
  return ans % m;
}

inline string to_str(int a) {
  char x[100];
  sprintf(x, "%lld", a);
  string s = x;
  return s;
}

inline int to_int(string a) {
  char x[100];
  int res;
  strcpy(x, a.c_str());
  sscanf(x, "%lld", &res);
  return res;
}

inline constexpr ll modulo(const ll n, const ll m = MOD) {
  ll k = n % m;
  return k + m * (k < 0);
}

inline ll inv(const ll n, const ll m = MOD) {
  ll a = n, b = m, x = 1, y = 0;
  while (b) {
    ll t = a / b;
    a -= t * b;
    swap(a, b);
    x -= t * y;
    swap(x, y);
  }
  return modulo(x, m);
}

// Debug

#define Debug(...)                                                             \
  {                                                                            \
    cerr << __LINE__ << ": " << #__VA_ARGS__ << " = ";                         \
    for (auto &&X : {__VA_ARGS__})                                             \
      cerr << "[" << X << "] ";                                                \
    cerr << endl;                                                              \
  }

#define vdump(a, x, y)                                                         \
  {                                                                            \
    cerr << __LINE__ << ": " << #a << " = [";                                  \
    rep(__i, x, y) if (__i) cerr << " " << a[__i];                             \
    else cerr << a[__i];                                                       \
    cerr << "]" << endl;                                                       \
  }

template <typename C,
          typename T = std::decay_t<decltype(*begin(std::declval<C>()))>,
          typename std::enable_if<!std::is_same<C, std::string>::value>::type
              * = nullptr>
std::ostream &operator<<(std::ostream &os, const C &container) {
  bool first = true;
  std::stringstream ss;
  cerr << '[';
  for (const auto &x : container) {
    if (!first) {
      cerr << ", ";
    }
    first = false;
    cerr << x;
  }
  cerr << ']';
  cerr << endl;
  return os << ss.str();
}

void solve() {
  int n, a, b;
  cin >> n >> a >> b;
  int ans = a * ((a + b - 1) / b) + min(n % (a + b), a);
  debug(ans);
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);

  int t = 1;
  // cin>>t;
  WL(t) { solve(); }

  cerr << "Time elapsed: " << clock() / 1000 << " ms" << endl;
}

Fixed submission:
// Author - Sumit

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;

#pragma GCC optimize("O3")
#pragma GCC target("avx")

#define ll long long
#define int ll
#define ps push
#define pb emplace_back
#define INF 1LL << 60
#define MOD 1e9 + 7
#define mp make_pair
#define rep(i, a, b) for (int i = a; i < b; i++)
#define repd(i, a, b) for (int i = a; i >= b; i--)
#define all(v) v.begin(), v.end()
#define pii pair<int, int>
#define F first
#define S second
#define mii map<int, int>
#define vi vector<int>
#define vvi vector<vi>
#define vpii vector<pair<int, int>>
#define itr ::iterator it
#define WL(t) while (t--)
#define gcd(a, b) __gcd((a), (b))
#define lcm(a, b) ((a) * (b)) / gcd((a), (b))
#define lower(v, x) (lower_bound(all(v), x) - v.begin())
#define upper(v, x) (upper_bound(all(v), x) - v.begin())
#define debug(x) cout << x << "\n";
#define debug2(x, y) cout << x << " " << y << "\n";
#define debug3(x, y, z) cout << x << " " << y << " " << z << endl;

typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    pbds;

template <typename T, typename U> inline void remin(T &x, U y) {
  if (y < x)
    x = y;
}
template <typename T, typename U> inline void remax(T &x, U y) {
  if (x < y)
    x = y;
}
template <typename T> T pow(T a, T b, T m) {
  T ans = 1;
  while (b > 0) {
    if (b % 2 == 1)
      ans = (ans * a) % m;
    b /= 2;
    a = (a * a) % m;
  }
  return ans % m;
}

inline string to_str(int a) {
  char x[100];
  sprintf(x, "%lld", a);
  string s = x;
  return s;
}

inline int to_int(string a) {
  char x[100];
  int res;
  strcpy(x, a.c_str());
  sscanf(x, "%lld", &res);
  return res;
}

inline constexpr ll modulo(const ll n, const ll m = MOD) {
  ll k = n % m;
  return k + m * (k < 0);
}

inline ll inv(const ll n, const ll m = MOD) {
  ll a = n, b = m, x = 1, y = 0;
  while (b) {
    ll t = a / b;
    a -= t * b;
    swap(a, b);
    x -= t * y;
    swap(x, y);
  }
  return modulo(x, m);
}

// Debug

#define Debug(...)                                                             \
  {                                                                            \
    cerr << __LINE__ << ": " << #__VA_ARGS__ << " = ";                         \
    for (auto &&X : {__VA_ARGS__})                                             \
      cerr << "[" << X << "] ";                                                \
    cerr << endl;                                                              \
  }

#define vdump(a, x, y)                                                         \
  {                                                                            \
    cerr << __LINE__ << ": " << #a << " = [";                                  \
    rep(__i, x, y) if (__i) cerr << " " << a[__i];                             \
    else cerr << a[__i];                                                       \
    cerr << "]" << endl;                                                       \
  }

template <typename C,
          typename T = std::decay_t<decltype(*begin(std::declval<C>()))>,
          typename std::enable_if<!std::is_same<C, std::string>::value>::type
              * = nullptr>
std::ostream &operator<<(std::ostream &os, const C &container) {
  bool first = true;
  std::stringstream ss;
  cerr << '[';
  for (const auto &x : container) {
    if (!first) {
      cerr << ", ";
    }
    first = false;
    cerr << x;
  }
  cerr << ']';
  cerr << endl;
  return os << ss.str();
}

void solve() {
  int n, a, b;
  cin >> n >> a >> b;
  if (a == 0) {
    debug(0);
    return;
  }
  if (b == 0) {
    debug(n);
    return;
  }
  int ans = (n / (a + b)) * a + min(n % (a + b), a);
  debug(ans);
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);

  int t = 1;
  // cin>>t;
  WL(t) { solve(); }

  cerr << "Time elapsed: " << clock() / 1000 << " ms" << endl;
}