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

#include "bits/stdc++.h"
#define rep(i, j) for (int i = 0; i < j; i++)
#define srep(i, j, k) for (int i = j; i < k; i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;
using ull = unsigned long long;

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

// �G���g�X�e�l�X���
vector<int> estora(vector<int> num) {
  int sel = 0;
  while (sel < num.size()) {
    int d = num[sel];
    for (int i = 0; i < num.size(); i++) {
      if (num[i] % d == 0 && num[i] != d && d != 1) {
        num.erase(num.begin() + i);
        i--;
      }
    }
    sel++;
  }
  return num;
}
/*���C�u�����ő����*/
// ���[�O���b�h�̌ݏ��@
int gcd(int x, int y) {
  int num[3];
  num[0] = (x > y) ? x : y;
  num[1] = (x <= y) ? x : y;
  num[2] = num[0] % num[1];

  while (num[2]) {
    num[0] = num[1];
    num[1] = num[2];
    num[2] = num[0] % num[1];
  }

  return num[1];
}

/*�f��������*/
// ���색�C�u����
// i����ɑf���ɂ��Ă����Ȃ��Ƃ��܂��ł��Ȃ�&&�v�Z�ʃ��o�C
// �G�X�g���l�X��⿂őf����U����Ă����K�v�������肻��
vector<ll> fac(ll n, vector<ll> num) {
  ll kazu = n;
  for (int i = 2; i <= n; i++) {
    while (1) {
      if (kazu % i != 0)
        break;

      kazu /= i;
      num[i]++;
    }
  }
  if (kazu == n && n != 1)
    num[n]++;
  return num;
  int ans = 0;
  if (kazu != 1)
    ans++;
  for (int i = 2; i <= sqrt(n); i++) {
    for (int j = 1; j <= num[i]; j++) {
      num[i] -= j;
      ans++;
    }
  }
  return num;
}
const int INF = 1001001001;

// mint�p�̒萔 (10��9�� + 7)
const int mod = 1000000007;

struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, const mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

int main() {
  ll x, k, d;
  cin >> x >> k >> d;
  ll mae = x;
  ll kai = 0;
  if (x >= 0) {
    kai = x / d;
    x -= kai * d;
  }
  if (x < 0) {
    kai = abs(x) / d;
    x += kai * d;
  }
  if (kai >= k) {
    mae = abs(mae) - k * d;
    cout << mae;
    return 0;
  }
  srep(i, kai, k) {
    mae = x;
    kai++;
    if (x >= 0) {
      x -= d;
      if (x <= 0) {
        break;
      }
    } else {
      x += d;
      if (x >= 0) {
        break;
      }
    }
  }
  if ((k - kai) % 2 == 1)
    x = mae;
  cout << abs(x) << endl;
  return 0;
}

Error: TLE

Fixed submission:

#include "bits/stdc++.h"
#define rep(i, j) for (int i = 0; i < j; i++)
#define srep(i, j, k) for (int i = j; i < k; i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;
using ull = unsigned long long;

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

// �G���g�X�e�l�X���
vector<int> estora(vector<int> num) {
  int sel = 0;
  while (sel < num.size()) {
    int d = num[sel];
    for (int i = 0; i < num.size(); i++) {
      if (num[i] % d == 0 && num[i] != d && d != 1) {
        num.erase(num.begin() + i);
        i--;
      }
    }
    sel++;
  }
  return num;
}
/*���C�u�����ő����*/
// ���[�O���b�h�̌ݏ��@
int gcd(int x, int y) {
  int num[3];
  num[0] = (x > y) ? x : y;
  num[1] = (x <= y) ? x : y;
  num[2] = num[0] % num[1];

  while (num[2]) {
    num[0] = num[1];
    num[1] = num[2];
    num[2] = num[0] % num[1];
  }

  return num[1];
}

/*�f��������*/
// ���색�C�u����
// i����ɑf���ɂ��Ă����Ȃ��Ƃ��܂��ł��Ȃ�&&�v�Z�ʃ��o�C
// �G�X�g���l�X��⿂őf����U����Ă����K�v�������肻��
vector<ll> fac(ll n, vector<ll> num) {
  ll kazu = n;
  for (int i = 2; i <= n; i++) {
    while (1) {
      if (kazu % i != 0)
        break;

      kazu /= i;
      num[i]++;
    }
  }
  if (kazu == n && n != 1)
    num[n]++;
  return num;
  int ans = 0;
  if (kazu != 1)
    ans++;
  for (int i = 2; i <= sqrt(n); i++) {
    for (int j = 1; j <= num[i]; j++) {
      num[i] -= j;
      ans++;
    }
  }
  return num;
}
const int INF = 1001001001;

// mint�p�̒萔 (10��9�� + 7)
const int mod = 1000000007;

struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, const mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

int main() {
  ll x, k, d;
  cin >> x >> k >> d;
  ll mae;
  ll kai = 0;
  rep(i, k) {
    mae = x;
    kai++;
    if (x >= 0) {
      x -= d;
      if (x <= 0) {
        break;
      }
    } else {
      x += d;
      if (x >= 0) {
        break;
      }
    }
  }
  if ((k - kai) % 2 == 1)
    x = mae;
  cout << abs(x) << endl;
  return 0;
}