Problem p02584 (C++) — buggy submission, verdict: Time Limit Exceeded

// atcoder/abc175/C/main.cpp
// author: @___Johniel
// github: https://github.com/johniel/

#include <bits/stdc++.h>

#define each(i, c) for (auto &i : c)
#define unless(cond) if (!(cond))

using namespace std;

template <typename P, typename Q>
ostream &operator<<(ostream &os, pair<P, Q> p) {
  os << "(" << p.first << "," << p.second << ")";
  return os;
}
template <typename P, typename Q>
istream &operator>>(istream &is, pair<P, Q> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, vector<T> v) {
  os << "(";
  for (auto &i : v)
    os << i << ",";
  os << ")";
  return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (auto &i : v)
    is >> i;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, set<T> s) {
  os << "#{";
  for (auto &i : s)
    os << i << ",";
  os << "}";
  return os;
}
template <typename K, typename V>
ostream &operator<<(ostream &os, map<K, V> m) {
  os << "{";
  for (auto &i : m)
    os << i << ",";
  os << "}";
  return os;
}

template <typename T> inline T setmax(T &a, T b) { return a = std::max(a, b); }
template <typename T> inline T setmin(T &a, T b) { return a = std::min(a, b); }

using lli = long long int;
using ull = unsigned long long;
using point = complex<double>;
using str = string;
template <typename T> using vec = vector<T>;

constexpr array<int, 8> di({0, 1, -1, 0, 1, -1, 1, -1});
constexpr array<int, 8> dj({1, 0, 0, -1, 1, -1, -1, 1});
constexpr lli mod = 1e9 + 7;

int main(int argc, char *argv[]) {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.setf(ios_base::fixed);
  cout.precision(15);

  lli x, k, d;
  while (cin >> x >> k >> d) {
    x = abs(x);
    const lli y = min(k, x / d);
    x -= y * d;
    k -= y;

    while (k && abs(x) > abs(x - d)) {
      --k;
      x = abs(x - d);
    }
    if (k) {
      k %= 2;
    }
    if (k) {
      x = min(abs(x - d), abs(x + d));
    }

    cout << x << endl;
  }

  return 0;
}


Error: TLE

Fixed submission:

// atcoder/abc175/C/main.cpp
// author: @___Johniel
// github: https://github.com/johniel/

#include <bits/stdc++.h>

#define each(i, c) for (auto &i : c)
#define unless(cond) if (!(cond))

using namespace std;

template <typename P, typename Q>
ostream &operator<<(ostream &os, pair<P, Q> p) {
  os << "(" << p.first << "," << p.second << ")";
  return os;
}
template <typename P, typename Q>
istream &operator>>(istream &is, pair<P, Q> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, vector<T> v) {
  os << "(";
  for (auto &i : v)
    os << i << ",";
  os << ")";
  return os;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (auto &i : v)
    is >> i;
  return is;
}
template <typename T> ostream &operator<<(ostream &os, set<T> s) {
  os << "#{";
  for (auto &i : s)
    os << i << ",";
  os << "}";
  return os;
}
template <typename K, typename V>
ostream &operator<<(ostream &os, map<K, V> m) {
  os << "{";
  for (auto &i : m)
    os << i << ",";
  os << "}";
  return os;
}

template <typename T> inline T setmax(T &a, T b) { return a = std::max(a, b); }
template <typename T> inline T setmin(T &a, T b) { return a = std::min(a, b); }

using lli = long long int;
using ull = unsigned long long;
using point = complex<double>;
using str = string;
template <typename T> using vec = vector<T>;

constexpr array<int, 8> di({0, 1, -1, 0, 1, -1, 1, -1});
constexpr array<int, 8> dj({1, 0, 0, -1, 1, -1, -1, 1});
constexpr lli mod = 1e9 + 7;

int main(int argc, char *argv[]) {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.setf(ios_base::fixed);
  cout.precision(15);

  lli x, k, d;
  while (cin >> x >> k >> d) {
    x = abs(x);
    const lli y = min(k, x / d);
    x -= y * d;
    k -= y;

    while (k) {
      if (x > abs(x - d)) {
        --k;
        continue;
      } else {
        if (2 <= k)
          k %= 2;
        else {
          x = min(abs(x + d), abs(x - d));
          --k;
        }
      }
    }
    cout << x << endl;
  }

  return 0;
}