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

#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string.h>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>
using namespace std;
#define sim template <class c
#define ris return *this
#define dor > debug &operator<<
#define eni(x)                                                                 \\
  sim > typename enable_if<sizeof dud<c>(0) x 1, debug &>::type operator<<(    \\
            c i) {
sim > struct rge {
  c b, e;
};
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c *x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
  ~debug() { cerr << endl; }
  eni(!=) cerr << boolalpha << i;
  ris;
} eni(==) ris << range(begin(i), end(i));
}
sim, class b dor(pair<b, c> d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
  sim dor(const c &) { ris; }
#endif
}
;
#define pp(...) "\\033[94m [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "]\\033[0m"
#define pp1(...)                                                               \\
  "\\033[1;47;35m" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "]\\033[0m"
#define dg(x) debug() << pp1(x)
#define dg1(x) debug() << "[line : " << __LINE__ << "]" << pp(x)
#define dg2(x, y) debug() << "[line : " << __LINE__ << "]" << pp(x) pp(y)
#define dg3(x, y, z)                                                           \\
  debug() << "[line : " << __LINE__ << "]" << pp(x) pp(y) pp(z)
#define dg4(w, x, y, z)                                                        \\
  debug() << "[line : " << __LINE__ << "]" << pp(w) pp(x) pp(y) pp(z)
#define int long long
#define all(x) x.begin(), x.end()
#define clr(x, y) memset(x, y, sizeof x);
#define sz(x) (int)x.size()
template <typename T> void db(T x) { debug() << ">>> " << x; }
template <typename T> void db(T x, T y) {
  debug() << ">>> " << x << " , " << y;
}
template <typename T> void db(T x, T y, T z) {
  debug() << ">>> " << x << " , " << y << " , " << z;
}
template <typename T> void db(T x, T y, T z, T a) {
  debug() << ">>> " << x << " , " << y << " , " << z << " , " << a;
}
const int xx = 2e5;
const int Mod = 1e9 + 7;
const int inf = 1e18;
const int Maxn = 20010;

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  int X, K, D;
  cin >> X >> K >> D;
  if (X < 0)
    X = X * -1;
  int cnt = min(K, X / D);
  K -= cnt;
  X -= (cnt * D);
  if (K % 2 == 0) {
    cout << X << '\\n';
  } else {
    cout << D - X << '\\n';
  }
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string.h>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>
using namespace std;
#define sim template <class c
#define ris return *this
#define dor > debug &operator<<
#define eni(x)                                                                 \\
  sim > typename enable_if<sizeof dud<c>(0) x 1, debug &>::type operator<<(    \\
            c i) {
sim > struct rge {
  c b, e;
};
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c *x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
  ~debug() { cerr << endl; }
  eni(!=) cerr << boolalpha << i;
  ris;
} eni(==) ris << range(begin(i), end(i));
}
sim, class b dor(pair<b, c> d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
  sim dor(const c &) { ris; }
#endif
}
;
#define pp(...) "\\033[94m [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "]\\033[0m"
#define pp1(...)                                                               \\
  "\\033[1;47;35m" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "]\\033[0m"
#define dg(x) debug() << pp1(x)
#define dg1(x) debug() << "[line : " << __LINE__ << "]" << pp(x)
#define dg2(x, y) debug() << "[line : " << __LINE__ << "]" << pp(x) pp(y)
#define dg3(x, y, z)                                                           \\
  debug() << "[line : " << __LINE__ << "]" << pp(x) pp(y) pp(z)
#define dg4(w, x, y, z)                                                        \\
  debug() << "[line : " << __LINE__ << "]" << pp(w) pp(x) pp(y) pp(z)
#define int long long
#define all(x) x.begin(), x.end()
#define clr(x, y) memset(x, y, sizeof x);
#define sz(x) (int)x.size()
template <typename T> void db(T x) { debug() << ">>> " << x; }
template <typename T> void db(T x, T y) {
  debug() << ">>> " << x << " , " << y;
}
template <typename T> void db(T x, T y, T z) {
  debug() << ">>> " << x << " , " << y << " , " << z;
}
template <typename T> void db(T x, T y, T z, T a) {
  debug() << ">>> " << x << " , " << y << " , " << z << " , " << a;
}
const int xx = 2e5;
const int Mod = 1e9 + 7;
const int inf = 1e18;
const int Maxn = 20010;
int cal(int pnt, int k, int x, int D) {
  int d = abs(x - pnt);
  int cnt = d / D;
  if ((k - cnt) % 2 == 0) {
    return abs(pnt);
  }
  return inf;
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int x, k, d;
  cin >> x >> k >> d;
  int ans = inf;
  for (int i = 1; i <= k; i++) {
    int l = x - (i * d);
    int r = x + (i * d);
    ans = min(ans, cal(l, k, x, d));
    ans = min(ans, cal(r, k, x, d));
  }
  if (k % 2 == 0)
    ans = min(ans, abs(x));
  cout << ans << '\\n';
}