Problem p00190 (C++) — buggy submission, verdict: Memory Limit Exceeded

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef tuple<int, int> duo;
const int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
const int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};
const int Mod = 1000000000 + 0;
//{{{ templates
#define TT_ template <typename T> inline
#define TTF_ template <typename T, typename F> inline
TT_ T sq(T x) { return x * x; }
TT_ T In() {
  T x;
  cin >> x;
  return x;
}
TT_ void Out(T &x) { cout << x; }
TT_ void sort(T &v) { sort(begin(v), end(v)); }
TT_ void revs(T &v) { reverse(begin(v), end(v)); }
TT_ void uniq(T &v) {
  sort(v);
  v.erase(unique(begin(v), end(v)), end(v));
}
TT_ int ubnd(T &v, typename T::value_type &x) {
  return upper_bound(begin(v), end(v), x) - begin(v);
}
TT_ int lbnd(T &v, typename T::value_type &x) {
  return lower_bound(begin(v), end(v), x) - begin(v);
}
TTF_ void inpt(T &v, int n, F f) {
  for (v.reserve(n); n--; v.emplace_back(f()))
    ;
}
TTF_ void show(T &v, F f, string d = " ", string e = "\\n") {
  int i = 0;
  for (auto &x : v)
    i++ && (cout << d), f(x);
  cout << e;
}
TT_ typename T::iterator minel(T &v) { return min_element(begin(v), end(v)); }
TT_ typename T::iterator maxel(T &v) { return max_element(begin(v), end(v)); }

inline void fast_io() {
  ios::sync_with_stdio(0);
  cin.tie(0);
}
inline int in() {
  int x;
  scanf("%d", &x);
  return x;
}
inline ll pow_mod(ll a, ll k, ll m) {
  ll r = 1;
  for (; k > 0; a = a * a % m, k >>= 1)
    if (k & 1)
      r = r * a % m;
  return r;
}
inline ll mod_inv(ll a, ll p) { return pow_mod(a, p - 2, p); }
//}}} priority_queue queue deque front stringstream max_element min_element
// insert count make_tuple

struct Board {
  Board() {
    memcpy(b, "0123456789AB0", sizeof(b));
    find_zero();
    turn = 0;
  }
  Board(const vector<int> &v) {
    for (int i = 0; i < 13; i++)
      b[i] = conv_hex(v[i]);
    b[13] = 0;
    find_zero();
    turn = 0;
  }
  void find_zero() {
    int it = 0;
    for (int i = 0; i < 13; i++) {
      if (b[i] == '0') {
        cur[it] = i;
        it++;
      }
    }
  }
  char conv_hex(int a) { return "0123456789ABCDEF"[a]; }
  bool slide(int index, int dir) {
    static const char mov[][4] = {
        {-1, -1, 2, -1},  {-1, 2, 5, -1},  {0, 3, 6, 1},   {-1, -1, 7, 2},
        {-1, 5, -1, -1},  {1, 6, 9, 4},    {2, 7, 10, 5},  {3, 8, 11, 6},
        {-1, -1, -1, 7},  {5, 10, -1, -1}, {6, 11, 12, 9}, {7, -1, -1, 10},
        {10, -1, -1, -1},
    };
    char cu = cur[index];
    char nu = mov[cu][dir];
    if (nu == -1)
      return false;
    if (b[nu] == '0')
      return false;
    swap(b[cu], b[nu]);
    cur[index] = nu;
    turn++;
    return true;
  }
  char b[14];
  char cur[2];
  char turn;
};

void build_table(unordered_map<ll, char> &ans) {
  Board b;
  queue<Board> Q;
  Q.push(b);
  while (!Q.empty()) {
    Board bi = Q.front();
    Q.pop();
    ll hv = strtoll(bi.b, 0, 16);
    if (ans.count(hv))
      continue;
    ans[hv] = bi.turn;
    if (bi.turn >= 10)
      continue;
    for (int i = 0; i < 2; i++) {
      for (int d = 0; d < 4; d++) {
        auto bii = bi;
        if (!bii.slide(i, d))
          continue;
        Q.push(bii);
      }
    }
  }
}

int main() {
  unordered_map<ll, char> ans;
  build_table(ans);
  int h;
  while (h = in(), h != -1) {
    vector<int> vs;
    vs.push_back(h);
    for (int i = 0; i < 12; i++)
      vs.push_back(in());
    Board b(vs);
    unordered_set<ll> vis;
    queue<Board> Q;
    Q.push(b);
    while (!Q.empty()) {
      Board bi = Q.front();
      Q.pop();
      ll hv = strtoll(bi.b, 0, 16);
      if (vis.count(hv))
        continue;
      vis.insert(hv);
      if (ans.count(hv)) {
        cout << (int)ans[hv] + (int)bi.turn << endl;
        goto END;
      }
      if (bi.turn >= 10)
        continue;
      for (int i = 0; i < 2; i++) {
        for (int d = 0; d < 4; d++) {
          Board bii = bi;
          if (!bii.slide(i, d))
            continue;
          Q.push(bii);
        }
      }
    }
    cout << "NA\\n";
  END:;
  }
  return 0;
}

Error: MLE

Fixed submission:

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef tuple<int, int> duo;
const int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
const int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};
const int Mod = 1000000000 + 0;
//{{{ templates
#define TT_ template <typename T> inline
#define TTF_ template <typename T, typename F> inline
TT_ T sq(T x) { return x * x; }
TT_ T In() {
  T x;
  cin >> x;
  return x;
}
TT_ void Out(T &x) { cout << x; }
TT_ void sort(T &v) { sort(begin(v), end(v)); }
TT_ void revs(T &v) { reverse(begin(v), end(v)); }
TT_ void uniq(T &v) {
  sort(v);
  v.erase(unique(begin(v), end(v)), end(v));
}
TT_ int ubnd(T &v, typename T::value_type &x) {
  return upper_bound(begin(v), end(v), x) - begin(v);
}
TT_ int lbnd(T &v, typename T::value_type &x) {
  return lower_bound(begin(v), end(v), x) - begin(v);
}
TTF_ void inpt(T &v, int n, F f) {
  for (v.reserve(n); n--; v.emplace_back(f()))
    ;
}
TTF_ void show(T &v, F f, string d = " ", string e = "\\n") {
  int i = 0;
  for (auto &x : v)
    i++ && (cout << d), f(x);
  cout << e;
}
TT_ typename T::iterator minel(T &v) { return min_element(begin(v), end(v)); }
TT_ typename T::iterator maxel(T &v) { return max_element(begin(v), end(v)); }

inline void fast_io() {
  ios::sync_with_stdio(0);
  cin.tie(0);
}
inline int in() {
  int x;
  scanf("%d", &x);
  return x;
}
inline ll pow_mod(ll a, ll k, ll m) {
  ll r = 1;
  for (; k > 0; a = a * a % m, k >>= 1)
    if (k & 1)
      r = r * a % m;
  return r;
}
inline ll mod_inv(ll a, ll p) { return pow_mod(a, p - 2, p); }
//}}} priority_queue queue deque front stringstream max_element min_element
// insert count make_tuple

struct Board {
  Board() {
    memcpy(b, "0123456789AB0", sizeof(b));
    find_zero();
  }
  Board(const vector<int> &v) {
    for (int i = 0; i < 13; i++)
      b[i] = conv_hex(v[i]);
    b[13] = 0;
    find_zero();
  }
  void find_zero() {
    int it = 0;
    for (int i = 0; i < 13; i++) {
      if (b[i] == '0') {
        cur[it] = i;
        it++;
      }
    }
  }
  char conv_hex(int a) { return "0123456789ABCDEF"[a]; }
  bool slide(int index, int dir) {
    static const char mov[][4] = {
        {-1, -1, 2, -1},  {-1, 2, 5, -1},  {0, 3, 6, 1},   {-1, -1, 7, 2},
        {-1, 5, -1, -1},  {1, 6, 9, 4},    {2, 7, 10, 5},  {3, 8, 11, 6},
        {-1, -1, -1, 7},  {5, 10, -1, -1}, {6, 11, 12, 9}, {7, -1, -1, 10},
        {10, -1, -1, -1},
    };
    char cu = cur[index];
    char nu = mov[cu][dir];
    if (nu == -1)
      return false;
    if (b[nu] == '0')
      return false;
    swap(b[cu], b[nu]);
    cur[index] = nu;
    turn++;
    return true;
  }
  char b[14];
  char cur[2];
  char turn;
};

int main() {
  int h;
  while (h = in(), h != -1) {
    vector<int> vs;
    vs.push_back(h);
    for (int i = 0; i < 12; i++)
      vs.push_back(in());
    Board b(vs);
    unordered_set<ll> vis;
    queue<Board> Q;
    Q.push(b);
    while (!Q.empty()) {
      Board bi = Q.front();
      Q.pop();
      ll hv = strtoll(bi.b, 0, 16);
      if (vis.count(hv))
        continue;
      vis.insert(hv);
      if (hv == 0x0123456789AB0ll) {
        cout << (int)bi.turn << endl;
        goto END;
      }
      if (bi.turn >= 20)
        continue;
      for (int i = 0; i < 2; i++) {
        for (int d = 0; d < 4; d++) {
          Board bii = bi;
          if (!bii.slide(i, d))
            continue;
          Q.emplace(move(bii));
        }
      }
    }
    cout << "NA\\n";
  END:;
  }
  return 0;
}