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


// Problem : F - Pond Skater
// Contest : AtCoder - AtCoder Beginner Contest 170
// URL : https://atcoder.jp/contests/abc170/tasks/abc170_f
// Memory Limit : 1024 MB
// Time Limit : 3000 ms
// Powered by CP Editor (https://github.com/cpeditor/cpeditor)

/* ID: vqt
LANG: C++14
PROB: namenum
*/

#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("Ofast")

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

// for PDBS use only:
//  #include <ext/pb_ds/assoc_container.hpp>
//  #include <ext/pb_ds/tree_policy.hpp>
//  using namespace __gnu_pbds;
//  template <typename T> using o_set = tree<T, null_type, greater<T>,
//  rb_tree_tag, tree_order_statistics_node_update>;
typedef long long ll;
// #define ordered_set tree<pair<ll,ll>, null_type,less<pair<ll,ll>>,
// rb_tree_tag,tree_order_statistics_node_update>

// defines
#define int long long
// #define double long double
#define vec vector
#define vi vector<int>
#define vvi vector<vector<int>>
#define ii pair<int, int>
#define F first
#define S second
#define MP make_pair
#define vii vector<ii>
#define PQ priority_queue
#define minPQ priority_queue<int, vt<int>, greater<int>>
#define PB push_back
#define LB lower_bound
#define UB upper_bound
#define ER equal_range
#define ALL(x) begin(x), end(x)
#define SZ(x) ((int)(x).size())
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define FORE(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (a); i >= (b); i--)
#define UNI(c) c.resize(distance(c.begin(), unique(c.begin(), c.end())));
#define SORT_UNI(c)                                                            \\
  (sort(c.begin(), c.end()),                                                   \\
   c.resize(distance(c.begin(), unique(c.begin(), c.end()))))
#define POS(c, x) (lower_bound(c.begin(), c.end(), (x)) - c.begin())
#define max(a, b) ((a) < (b) ? b : a)
#define min(a, b) ((a) < (b) ? a : b)
#define setmin(a, b) a = min(a, b)
#define setmax(a, b) a = max(a, b)
#define MINMAX(x) minmax_element(begin(x), end(x))

// permanent constants
const long long INF64 = 1e18;
const int INF32 = 1e9;
const double EPS = static_cast<double>(1e-10);
const double PI = 2.0 * acos(0.0); // acos(-1.0L);
const int MOD = (int)1e9 + 7;      // 998244353
ll powMod(ll a, ll b) {
  ll res = 1;
  a %= MOD;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1)
      res = res * a % MOD;
    a = a * a % MOD;
  }
  return res;
}
ll invMod(ll a) {
  ll b = MOD, u = 1, v = 0;
  while (b) {
    ll t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  return (MOD + u) % MOD;
}
const int day[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

// random
mt19937 rnd(
    239); //(chrono::high_resolution_clock::now().time_since_epoch().count());

// Tricks:
//  Sort w Lambda Function: sort(begin(v), end(v), [] (int a, int b) { return a
//  > b; }); Sort vector cua bo ba so: struct MyStr {int a, b, c;};
//  vector<MyStr> v; ...fill v... sort(all(v), [](MyStr &A, MyStr &B) { return
//  tie(A.a, A.b, A.c) < tie(B.a, B.b, B.c); });
#define odd(x) ((x)&1)
#define even(x) !((x)&1)
// vec - vector, p(x) - predicate so that p(x) = true for all elements of some
// prefix of vector vec and false on all others. To find the first place where
// p(x) doesn't hold one can simply use:
#define FIRST_FAIL(vec, p) partition_point(ALL(vec), p) - vec.begin()
// partition_point(begin, end, p) returns the first ITERATOR it that p(*it) =
// false
#define isIn(vec, key) binary_search(ALL(vec), key)
#define toBool(num) !!(num)
#define bin(N, num) cerr << bitset<N>(num) << "\\n"
// vector a: tinh XOR sum tu l den r:
#define XORsum(a, l, r)                                                        \\
  accumulate(a.begin() + l - 1, a.begin() + r, 0,                              \\
             [](int x, int y) { return x ^ y; })
// BASIC STRING: just like vector but allows to use a few string member
// functions/operators: operator+ and operator+=.:
/*  int n;    basic_string<int> a;
    cin >> n; FOR(i, 0, n) { int x;   cin >> x; a += x; }
    a += a; a = a.substr(n/2, n);
    cout << (a + a).find({1, 2, 1}) << '\\n';
*/
// count(a.begin(), a.end(), val) - count how many val in an array a
vector<int> prefixSum(vector<int> &a) {
  vi b;
  std::partial_sum(a.begin(), a.end(), b.begin());
  return b;
}

int mostSignDigit(int n) {
  double k = log10(n);
  return (int)pow(10, k - floor(k));
}
int numOfDigits(int n) { return (int)floor(log10(n)) + 1; }
bool isPowerOfTwo(int x) {
  return x && (!(x & (x - 1)));
} // first x is for the case x=0

bool allPositive(vector<int> &a) {
  return all_of(begin(a), end(a), [](int x) { return x > 0; });
} // are all of the elements positive?
// CHECK there is all numbers in array is positive: bool ok=true; for(auto z: a)
// ok &= (z>0);
bool anyPositive(vector<int> &a) {
  return any_of(begin(a), end(a), [](int x) { return x > 0; });
} // is there at least one positive element?
bool nonePositive(vector<int> &a) {
  return none_of(begin(a), end(a), [](int x) { return x > 0; });
} // are none of the elements positive?

void FILEIO() {
  freopen("in.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
}
// void FILEIO() {  freopen("berries.in", "r", stdin);  freopen("berries.out",
// "w", stdout); } // USACO

/****************** DEBUG *******************/
// Universal DEBUG: https://codeforces.com/blog/entry/68809
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
// void __print(long long x) {cerr << x;}
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\\'' << x << '\\''; }
void __print(const char *x) { cerr << '\\"' << x << '\\"'; }
void __print(const string &x) { cerr << '\\"' << x << '\\"'; }
void __print(bool x) { cerr << (x ? "T" : "F"); }
template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}

#define ONLINE_JUDGE
#ifndef ONLINE_JUDGE
#define debug(x...)                                                            \\
  cerr << "[" << #x << "] = [";                                                \\
  _print(x)
#else
#define debug(x...)
#endif
//********************** Codes go here *********************/
#define pi pair<int, ii>

int h, w, k;
bool valid(ii p) { return p.F >= 0 and p.F < h and p.S >= 0 and p.S < w; }

int val(ii p, vvi &v) { return v[p.F][p.S]; }

void solve() {
  cin >> h >> w >> k;
  ii s, t;
  cin >> s.F >> s.S >> t.F >> t.S;
  s.F--, s.S--, t.F--, t.S--;
  vvi c(h, vi(w, 0));
  FOR(i, 0, h) FOR(j, 0, w) {
    char cc;
    cin >> cc;
    c[i][j] = (cc == '@' ? 1 : 0);
  }
  vec<set<int>> row(h, set<int>()),
      col(w, set<int>()); // each row and col is a set of unvisited cells
  FOR(i, 0, h) FOR(j, 0, w) {
    row[i].insert(j);
    col[j].insert(i);
  }

  debug(s, t);

  queue<pi> q; // int = distance from s, ii - current point
  q.push(MP(0, s));

  debug(c);
  debug(row);
  debug(col);

  while (SZ(q)) {

    // queue<pi> qq = q; while(SZ(qq)) {debug(qq.front()); qq.pop();}

    pi p = q.front();
    q.pop();
    ii ps = p.S;
    row[ps.F].erase(ps.S);
    col[ps.S].erase(ps.F);

    // debug(p); debug(row); debug(col);

    set<ii> neib;
    auto r0 = row[ps.F].UB(ps.S), r1 = row[ps.F].UB(ps.S + k);
    for (auto it = r0; it != r1; ++it) {
      ii dd = MP(ps.F, *it);
      if (!valid(dd) or val(dd, c) == 1)
        break;
      neib.insert(dd);
    }

    debug(ps.F, row[7]);

    auto l0 = row[ps.F].LB(ps.S), l1 = row[ps.F].LB(ps.S - k);

    debug(*l0, *l1);

    auto itr = l0;
    while (1) {
      if (l1 == l0)
        break;
      if (itr != row[ps.F].begin())
        itr--;
      else
        break;
      ii dd = MP(ps.F, *itr);
      if (!valid(dd) or val(dd, c) == 1)
        break;
      neib.insert(dd);
      if (itr == l1)
        break;
    }

    auto d0 = col[ps.S].UB(ps.F), d1 = col[ps.S].UB(ps.F + k);
    for (auto it = d0; it != d1; ++it) {
      ii dd = MP(*it, ps.S);
      if (!valid(dd) or val(dd, c) == 1)
        break;
      neib.insert(dd);
    }
    auto u0 = col[ps.S].LB(ps.F), u1 = col[ps.S].LB(ps.F - k);
    auto itc = u0;
    while (1) {
      if (u1 == u0)
        break;
      if (itc != col[ps.S].begin())
        itc--;
      else
        break;
      ii dd = MP(*itc, ps.S);
      if (!valid(dd) or val(dd, c) == 1)
        break;
      neib.insert(dd);
      if (itc == u1)
        break;
    }

    debug(p, neib);

    for (auto x : neib) {
      if (x == t) {
        cout << p.F + 1 << endl;
        return;
      }
      pi go = {p.F + 1, x};
      q.push(go);
      row[x.F].erase(x.S);
      col[x.S].erase(x.F);
    }
  }
  cout << -1 << endl;
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie();
  // FILEIO();
  //  auto beginProgram = chrono::steady_clock::now();

  // preCalc(); // any 1-time precalculation need to do before many test cases?

  // int t; cin >> t; FORE(i, 1, t)
  {
    // cout << "Case #" << i << ": "; // Google CodeJam style
    solve();
  }

  //  auto endProgram = chrono::steady_clock::now();
  //  cerr << chrono::duration_cast<chrono::milliseconds>(endProgram -
  //  beginProgram).count() << " ms" << endl;
  return 0;
}

Error: TLE

Fixed submission:


// Problem : F - Pond Skater
// Contest : AtCoder - AtCoder Beginner Contest 170
// URL : https://atcoder.jp/contests/abc170/tasks/abc170_f
// Memory Limit : 1024 MB
// Time Limit : 3000 ms
// Powered by CP Editor (https://github.com/cpeditor/cpeditor)

/* ID: vqt
LANG: C++14
PROB: namenum
*/

#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("Ofast")

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

// for PDBS use only:
//  #include <ext/pb_ds/assoc_container.hpp>
//  #include <ext/pb_ds/tree_policy.hpp>
//  using namespace __gnu_pbds;
//  template <typename T> using o_set = tree<T, null_type, greater<T>,
//  rb_tree_tag, tree_order_statistics_node_update>;
typedef long long ll;
// #define ordered_set tree<pair<ll,ll>, null_type,less<pair<ll,ll>>,
// rb_tree_tag,tree_order_statistics_node_update>

// defines
#define int long long
// #define double long double
#define vec vector
#define vi vector<int>
#define vvi vector<vector<int>>
#define ii pair<int, int>
#define F first
#define S second
#define MP make_pair
#define vii vector<ii>
#define PQ priority_queue
#define minPQ priority_queue<int, vt<int>, greater<int>>
#define PB push_back
#define LB lower_bound
#define UB upper_bound
#define ER equal_range
#define ALL(x) begin(x), end(x)
#define SZ(x) ((int)(x).size())
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define FORE(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (a); i >= (b); i--)
#define UNI(c) c.resize(distance(c.begin(), unique(c.begin(), c.end())));
#define SORT_UNI(c)                                                            \\
  (sort(c.begin(), c.end()),                                                   \\
   c.resize(distance(c.begin(), unique(c.begin(), c.end()))))
#define POS(c, x) (lower_bound(c.begin(), c.end(), (x)) - c.begin())
#define max(a, b) ((a) < (b) ? b : a)
#define min(a, b) ((a) < (b) ? a : b)
#define setmin(a, b) a = min(a, b)
#define setmax(a, b) a = max(a, b)
#define MINMAX(x) minmax_element(begin(x), end(x))

// permanent constants
const long long INF64 = 1e18;
const int INF32 = 1e9;
const double EPS = static_cast<double>(1e-10);
const double PI = 2.0 * acos(0.0); // acos(-1.0L);
const int MOD = (int)1e9 + 7;      // 998244353
ll powMod(ll a, ll b) {
  ll res = 1;
  a %= MOD;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1)
      res = res * a % MOD;
    a = a * a % MOD;
  }
  return res;
}
ll invMod(ll a) {
  ll b = MOD, u = 1, v = 0;
  while (b) {
    ll t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  return (MOD + u) % MOD;
}
const int day[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

// random
mt19937 rnd(
    239); //(chrono::high_resolution_clock::now().time_since_epoch().count());

// Tricks:
//  Sort w Lambda Function: sort(begin(v), end(v), [] (int a, int b) { return a
//  > b; }); Sort vector cua bo ba so: struct MyStr {int a, b, c;};
//  vector<MyStr> v; ...fill v... sort(all(v), [](MyStr &A, MyStr &B) { return
//  tie(A.a, A.b, A.c) < tie(B.a, B.b, B.c); });
#define odd(x) ((x)&1)
#define even(x) !((x)&1)
// vec - vector, p(x) - predicate so that p(x) = true for all elements of some
// prefix of vector vec and false on all others. To find the first place where
// p(x) doesn't hold one can simply use:
#define FIRST_FAIL(vec, p) partition_point(ALL(vec), p) - vec.begin()
// partition_point(begin, end, p) returns the first ITERATOR it that p(*it) =
// false
#define isIn(vec, key) binary_search(ALL(vec), key)
#define toBool(num) !!(num)
#define bin(N, num) cerr << bitset<N>(num) << "\\n"
// vector a: tinh XOR sum tu l den r:
#define XORsum(a, l, r)                                                        \\
  accumulate(a.begin() + l - 1, a.begin() + r, 0,                              \\
             [](int x, int y) { return x ^ y; })
// BASIC STRING: just like vector but allows to use a few string member
// functions/operators: operator+ and operator+=.:
/*  int n;    basic_string<int> a;
    cin >> n; FOR(i, 0, n) { int x;   cin >> x; a += x; }
    a += a; a = a.substr(n/2, n);
    cout << (a + a).find({1, 2, 1}) << '\\n';
*/
// count(a.begin(), a.end(), val) - count how many val in an array a
vector<int> prefixSum(vector<int> &a) {
  vi b;
  std::partial_sum(a.begin(), a.end(), b.begin());
  return b;
}

int mostSignDigit(int n) {
  double k = log10(n);
  return (int)pow(10, k - floor(k));
}
int numOfDigits(int n) { return (int)floor(log10(n)) + 1; }
bool isPowerOfTwo(int x) {
  return x && (!(x & (x - 1)));
} // first x is for the case x=0

bool allPositive(vector<int> &a) {
  return all_of(begin(a), end(a), [](int x) { return x > 0; });
} // are all of the elements positive?
// CHECK there is all numbers in array is positive: bool ok=true; for(auto z: a)
// ok &= (z>0);
bool anyPositive(vector<int> &a) {
  return any_of(begin(a), end(a), [](int x) { return x > 0; });
} // is there at least one positive element?
bool nonePositive(vector<int> &a) {
  return none_of(begin(a), end(a), [](int x) { return x > 0; });
} // are none of the elements positive?

void FILEIO() {
  freopen("in.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
}
// void FILEIO() {  freopen("berries.in", "r", stdin);  freopen("berries.out",
// "w", stdout); } // USACO

/****************** DEBUG *******************/
// Universal DEBUG: https://codeforces.com/blog/entry/68809
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
// void __print(long long x) {cerr << x;}
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\\'' << x << '\\''; }
void __print(const char *x) { cerr << '\\"' << x << '\\"'; }
void __print(const string &x) { cerr << '\\"' << x << '\\"'; }
void __print(bool x) { cerr << (x ? "T" : "F"); }
template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}

#define ONLINE_JUDGE
#ifndef ONLINE_JUDGE
#define debug(x...)                                                            \\
  cerr << "[" << #x << "] = [";                                                \\
  _print(x)
#else
#define debug(x...)
#endif
//********************** Codes go here *********************/
#define pi pair<int, ii>

int h, w, k;
bool valid(ii p) { return p.F >= 0 and p.F < h and p.S >= 0 and p.S < w; }

int val(ii p, vvi &v) { return v[p.F][p.S]; }

void solve() {
  cin >> h >> w >> k;
  ii s, t;
  cin >> s.F >> s.S >> t.F >> t.S;
  s.F--, s.S--, t.F--, t.S--;
  vvi c(h, vi(w, 0)), vis(h, vi(w, 0));
  FOR(i, 0, h) FOR(j, 0, w) {
    char cc;
    cin >> cc;
    c[i][j] = (cc == '@' ? 1 : 0);
  }
  queue<pi> q; // int = distance from s, ii - current point
  vec<ii> dir = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
  q.push(MP(0, s));
  vis[s.F][s.S] = 1;

  debug(c);
  debug(vis);

  while (SZ(q)) {
    pi p = q.front();
    q.pop();

    debug(p);

    FOR(i, 0, 4) {
      ii d = dir[i];

      debug(i, d);

      int step = 1;
      ii dd = p.S; //{p.S.F, p.S.S};
      while (step <= k) {
        dd = {dd.F + d.F, dd.S + d.S};
        pi go = {p.F + 1, dd};

        debug(step, dd, go, valid(dd));

        if (!valid(dd) or val(dd, c) == 1) {
          // cerr << "Break!" << endl;
          break;
        }

        debug(val(dd, vis));

        if (val(dd, vis) == 1) {
          step++;
          continue;
        }

        debug(dd, t);

        if (dd == t) {
          cout << go.F << endl;
          return;
        }
        vis[dd.F][dd.S] = 1;
        q.push(go);
        step++;
      }
    }
  }
  cout << -1 << endl;
}

signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie();
  // FILEIO();
  //  auto beginProgram = chrono::steady_clock::now();

  // preCalc(); // any 1-time precalculation need to do before many test cases?

  // int t; cin >> t; FORE(i, 1, t)
  {
    // cout << "Case #" << i << ": "; // Google CodeJam style
    solve();
  }

  //  auto endProgram = chrono::steady_clock::now();
  //  cerr << chrono::duration_cast<chrono::milliseconds>(endProgram -
  //  beginProgram).count() << " ms" << endl;
  return 0;
}