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

/*input
3 3 1
2 1 2 3
.@.
.@.
.@.
*/

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <unistd.h>

#define rep(i, j, n) for (i = j; i < n; i++)
#define repi(i, j, n) for (i = j; i > n; i--)
#define inf 1e9
#define M 1000000007
#define pie 3.141592653589793238
#define ll long long
#define ld long double
#define vll vector<ll>
#define pll pair<ll, ll>
#define vpll vector<pll>
#define pb push_back
#define F first
#define S second
#define endl '\\n'
#define UQ(x) (x).resize(distance((x).begin(), unique(all((x)))))

using namespace std;
using namespace __gnu_pbds;

template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

mt19937 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64
    rnd64(chrono::high_resolution_clock::now().time_since_epoch().count());

ll power(ll a, ll m, ll mod) {
  ll ans = 1;
  while (m) {
    if (m % 2) {
      ans *= a;
      ans %= (mod);
    }
    a = (a * a) % (mod);
    m >>= 1;
  }
  return ans;
}

void init(ll *a, ll n, ll val) {
  for (ll i = 0; i < n; i++)
    a[i] = val;
}

ll dx[4] = {1, 0, -1, 0};
ll dy[4] = {0, 1, 0, -1};

void solve() {
  ll i, j, _;
  ll h, w, k;
  cin >> h >> w >> k;
  char ch;
  ll x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2, --x1, --x2, --y1, --y2;
  ll a[h][w];
  ld b[h][w][4];
  rep(i, 0, h) {
    rep(j, 0, w) {
      cin >> ch;
      a[i][j] = (ch == '.');
      rep(_, 0, 4) b[i][j][_] = inf;
    }
  }
  if (!a[x1][y1] || !a[x2][y2]) {
    cout << -1 << endl;
    return;
  }
  rep(i, 0, 4) b[x1][y1][i] = 0;
  set<pair<pair<ld, ll>, pll>> st;
  st.insert({{0, 0}, {x1, y1}});
  pll z;
  ld tmp, tmp2;
  ll x, y, dir;
  while (st.size()) {
    auto it = st.begin();
    z = (*it).S, dir = (*it).F.S, tmp = (*it).F.F, tmp2 = tmp;
    st.erase(it);
    rep(i, 0, 4) {
      tmp = tmp2;
      x = z.F + dx[i], y = z.S + dy[i];
      if (x < 0 || y < 0 || x > h - 1 || y > w - 1 || !a[x][y])
        continue;
      if (dir == i) {
        tmp += 1 / (ld)k;
      } else {
        tmp = ceil(tmp);
        tmp += 1 / (ld)k;
      }
      if (tmp >= b[x][y][i])
        continue;
      b[x][y][i] = tmp;
      st.insert({{tmp, i}, {x, y}});
    }
  }
  ll ans = inf;
  rep(i, 0, 4) ans = min(ans, (ll)ceil(b[x2][y2][i]));
  if (ans == inf)
    ans = -1;
  cout << ans << endl;
}

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  ll T = 1;
  // cin>>T;
  while (T--) {
    solve();
  }
  return 0;
}


Error: TLE

Fixed submission:

/*input
3 3 1
2 1 2 3
.@.
.@.
.@.
*/

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <unistd.h>

#define rep(i, j, n) for (i = j; i < n; i++)
#define repi(i, j, n) for (i = j; i > n; i--)
#define inf 1e9
#define M 1000000007
#define pie 3.141592653589793238
#define ll long long
#define ld long double
#define vll vector<ll>
#define pll pair<ll, ll>
#define vpll vector<pll>
#define pb push_back
#define F first
#define S second
#define endl '\\n'
#define UQ(x) (x).resize(distance((x).begin(), unique(all((x)))))

using namespace std;
using namespace __gnu_pbds;

template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

mt19937 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64
    rnd64(chrono::high_resolution_clock::now().time_since_epoch().count());

ll power(ll a, ll m, ll mod) {
  ll ans = 1;
  while (m) {
    if (m % 2) {
      ans *= a;
      ans %= (mod);
    }
    a = (a * a) % (mod);
    m >>= 1;
  }
  return ans;
}

void init(ll *a, ll n, ll val) {
  for (ll i = 0; i < n; i++)
    a[i] = val;
}

ll dx[4] = {1, 0, -1, 0};
ll dy[4] = {0, 1, 0, -1};
vector<vector<vector<vector<ld>>>> b;

void solve() {
  ll i, j, _, __;
  ll h, w, k;
  cin >> h >> w >> k;
  char ch;
  ll x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2, --x1, --x2, --y1, --y2;
  ll a[h][w];
  b.resize(h,
           vector<vector<vector<ld>>>(w, vector<vector<ld>>(4, vector<ld>(4))));
  rep(i, 0, h) {
    rep(j, 0, w) {
      cin >> ch;
      a[i][j] = (ch == '.');
      rep(_, 0, 4) rep(__, 0, 4) b[i][j][_][__] = inf;
    }
  }
  if (!a[x1][y1] || !a[x2][y2]) {
    cout << -1 << endl;
    return;
  }
  rep(i, 0, 4) rep(j, 0, 4) b[x1][y1][i][j] = 0;
  set<pair<pair<ld, ll>, pll>> st;
  st.insert({{0, 0}, {x1, y1}});
  pll z;
  ld tmp, tmp2;
  ll x, y, dir;
  while (st.size()) {
    auto it = st.begin();
    z = (*it).S, dir = (*it).F.S, tmp = (*it).F.F, tmp2 = tmp;
    st.erase(it);
    rep(i, 0, 4) {
      tmp = tmp2;
      x = z.F + dx[i], y = z.S + dy[i];
      if (x < 0 || y < 0 || x > h - 1 || y > w - 1 || !a[x][y] ||
          b[x][y][i][dir] < inf)
        continue;
      if (dir == i) {
        tmp += 1 / (ld)k;
      } else {
        tmp = ceil(tmp);
        tmp += 1 / (ld)k;
      }
      ld tt = tmp - (1 / (ld)k) * k;
      if (ceil(tt) == tt)
        tmp = ceil(tmp);
      b[x][y][i][dir] = tmp;
      st.insert({{tmp, i}, {x, y}});
    }
  }
  ll ans = inf;
  rep(i, 0, 4) rep(j, 0, 4) ans = min(ans, (ll)ceil(b[x2][y2][i][j]));
  if (ans == inf)
    ans = -1;
  cout << ans << endl;
}

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  ll T = 1;
  // cin>>T;
  while (T--) {
    solve();
  }
  return 0;
}