Problem p02644 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;

inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef vector<vector<long long>> VVL;
typedef vector<string> VS;
typedef pair<int, int> P;
typedef tuple<int, int, int> tpl;

#define ALL(a) (a).begin(), (a).end()
#define SORT(c) sort((c).begin(), (c).end())
#define REVERSE(c) reverse((c).begin(), (c).end())
#define EXIST(m, v) (m).find((v)) != (m).end()
#define LB(a, x) lower_bound((a).begin(), (a).end(), x) - (a).begin()
#define UB(a, x) upper_bound((a).begin(), (a).end(), x) - (a).begin()

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define RFOR(i, a, b) for (int i = (a)-1; i >= (b); --i)
#define RREP(i, n) RFOR(i, n, 0)

#define en "\\n"

constexpr double EPS = 1e-9;
constexpr double PI = 3.1415926535897932;
constexpr int INF = 2147483647;
constexpr long long LINF = 1LL << 60;
constexpr long long MOD = 1000000007; // 998244353;

#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

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;
}

void Main() {
  int H, W, K;
  cin >> H >> W >> K;
  VI x(4);
  REP(i, 4) {
    cin >> x[i];
    x[i]--;
  }
  char c[H][W];
  REP(i, H) REP(j, W) cin >> c[i][j];

  int d[H][W];
  REP(i, H) REP(j, W) d[i][j] = INF;
  d[x[0]][x[1]] = 0;

  queue<int> q;
  q.emplace(x[0] * W + x[1]);
  while (!q.empty()) {
    int loc = q.front();
    q.pop();
    int s = loc / W, t = loc % W;
    int cost = d[s][t];

    REP(i, K) {
      if (s - i - 1 < 0 || c[s - i - 1][t] == '@')
        break;
      if (d[s - i - 1][t] <= cost)
        break;
      if (chmin(d[s - i - 1][t], cost + 1))
        q.emplace((s - i - 1) * W + t);
    }
    REP(i, K) {
      if (s + i + 1 >= H || c[s + i + 1][t] == '@')
        break;
      if (d[s + i + 1][t] <= cost)
        break;
      if (chmin(d[s + i + 1][t], cost + 1))
        q.emplace((s + i + 1) * W + t);
    }
    REP(i, K) {
      if (t - i - 1 < 0 || c[s][t - i - 1] == '@')
        break;
      if (d[s][t - i - 1] <= cost)
        break;
      if (chmin(d[s][t - i - 1], cost + 1))
        q.emplace(s * W + t - i - 1);
    }
    REP(i, K) {
      if (t + i + 1 >= W || c[s][t + i + 1] == '@')
        break;
      if (d[s][t + i + 1] <= cost)
        break;
      if (chmin(d[s][t + i + 1], cost + 1))
        q.emplace(s * W + t + i + 1);
    }
  }

  int ans = d[x[2]][x[3]] < INF ? d[x[2]][x[3]] : -1;
  cout << ans << en;
  return;
}

int main(void) {
  cin.tie(0);
  cout.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(15);
  int t = 1; // cin>>t;
  REP(_, t) Main();
  return 0;
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;

inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef vector<vector<long long>> VVL;
typedef vector<string> VS;
typedef pair<int, int> P;
typedef tuple<int, int, int> tpl;

#define ALL(a) (a).begin(), (a).end()
#define SORT(c) sort((c).begin(), (c).end())
#define REVERSE(c) reverse((c).begin(), (c).end())
#define EXIST(m, v) (m).find((v)) != (m).end()
#define LB(a, x) lower_bound((a).begin(), (a).end(), x) - (a).begin()
#define UB(a, x) upper_bound((a).begin(), (a).end(), x) - (a).begin()

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define RFOR(i, a, b) for (int i = (a)-1; i >= (b); --i)
#define RREP(i, n) RFOR(i, n, 0)

#define en "\\n"

constexpr double EPS = 1e-9;
constexpr double PI = 3.1415926535897932;
constexpr int INF = 2147483647;
constexpr long long LINF = 1LL << 60;
constexpr long long MOD = 1000000007; // 998244353;

#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

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;
}

void Main() {
  int H, W, K;
  cin >> H >> W >> K;
  VI x(4);
  REP(i, 4) {
    cin >> x[i];
    x[i]--;
  }
  char c[H][W];
  REP(i, H) REP(j, W) cin >> c[i][j];

  int d[H][W];
  REP(i, H) REP(j, W) d[i][j] = INF;
  d[x[0]][x[1]] = 0;

  queue<int> q;
  q.emplace(x[0] * W + x[1]);
  while (!q.empty()) {
    int loc = q.front();
    q.pop();
    int s = loc / W, t = loc % W;
    int cost = d[s][t];

    REP(i, K) {
      if (s - i - 1 < 0 || c[s - i - 1][t] == '@')
        break;
      if (chmin(d[s - i - 1][t], cost + 1))
        q.emplace((s - i - 1) * W + t);
    }
    REP(i, K) {
      if (s + i + 1 >= H || c[s + i + 1][t] == '@')
        break;
      if (chmin(d[s + i + 1][t], cost + 1))
        q.emplace((s + i + 1) * W + t);
    }
    REP(i, K) {
      if (t - i - 1 < 0 || c[s][t - i - 1] == '@')
        break;
      if (chmin(d[s][t - i - 1], cost + 1))
        q.emplace(s * W + t - i - 1);
    }
    REP(i, K) {
      if (t + i + 1 >= W || c[s][t + i + 1] == '@')
        break;
      if (chmin(d[s][t + i + 1], cost + 1))
        q.emplace(s * W + t + i + 1);
    }
  }

  int ans = d[x[2]][x[3]] < INF ? d[x[2]][x[3]] : -1;
  cout << ans << en;
  return;
}

int main(void) {
  cin.tie(0);
  cout.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(15);
  int t = 1; // cin>>t;
  REP(_, t) Main();
  return 0;
}