Language: C++

#include<iostream>
#include<cmath>
#include<string>
#include<map>
#include<queue>

using namespace std;

#define N 4
#define N2 16
#define LIMIT 100

static const int dx[4] = {0, -1, 0, 1};
static const int dy[4] = {1, 0, -1, 0};
static const char dir[4] = {'r', 'u', 'l', 'd'};
int MDT[N2][N2];

struct Puzzle {
  int f[N2];
  int space;
  int MD;
  int cost;

  bool operator < (const Puzzle& p) const {
    for (int i = 0; i < N2; i++) {
      if (f[i] == p.f[i]) {
        continue;
      }
      return f[i] < p.f[i];
    }
    return false;
  }
};

struct State {
  Puzzle puzzle;
  int estimated;
  bool operato < (const State& s) const {
    return estimated > s.estimated;
  }
};

int getAllMD(Puzzle pz) {
  int sum = 0;
  for (int i = 0; i < N2; i++) {
    if (pz.f[i] == N2) {
      continue;
    }
    sum += MDT[i][pz.f[i] - 1];
  }
  return sum;
}

bool isSolved() {
  for (int i = 0; i < N2; i++) {
    if (state.f[i] != i + 1) {
      return false;
    }
  }
  return true;
}

int astat(Puzzle pz) {
  priority_queue<State> PQ;
  s.MD = getAllMD(s);
  s.cost = 0;
  map<Puzzle, bool> V;
  Puzzle u, v;
  State initial;
  initial.puzzle = s;
  initial.estimated = getAllMD(s);
  PQ.push(initial);

  while (!PQ.empty()) {
    State st = PQ.top(); PQ.pop();
    u = st.puzzle;

    if (u.MD == 0) {
      return u.cost;
    }
    V[u] = true;

    int sx = u.space / N;
    int sy = u.space % N;

    for (int r = 0; r < 4; r++) {
      int tx = sx + dx[r];
      int ty = sy + dy[r];
      if (tx < 0 || ty < 0 || tx >= N || ty >= N) {
        continue;
      }
      v = u;

      v.MD -= MDT[tx * N + ty][v.f[tx * N + ty] - 1];
      v.MD += MDT[sx * N + sy][v.f[tx * N + ty] - 1];
      swap(v.f[sx * N + sy], v.f[tx * N + ty]);
      v.space = tx * N + ty;
      if (!V[v]) {
        v.cost++;
        State news;
        news.puzzle = v;
        news.estimated = v.cost + v.MD;
        PQ.push(news);
      }
    }
  }
  return -1;
}

int main(){
  for (int i = 0; i < N2; i++) {
    for (int j = 0; j < N2; j++) {
      MDT[i][j] = abs(i / N - j / N) + abs(i % N - j % N);
    }
  }

  Puzzle in;

  for (int i = 0; i < N2; i++) {
    cin >> in.f[i];
    if (in.f[i] == 0) {
      in.f[i] = N2;
      in.space = i;
    }
  }

  cout << astar(in) << endl;

  return 0;
}




Compiler output:
a.cc:38:8: error: expected ';' at end of member declaration
   38 |   bool operato < (const State& s) const {
      |        ^~~~~~~
      |               ;
a.cc:38:16: error: expected unqualified-id before '<' token
   38 |   bool operato < (const State& s) const {
      |                ^
a.cc: In function 'bool isSolved()':
a.cc:56:9: error: 'state' was not declared in this scope; did you mean 'State'?
   56 |     if (state.f[i] != i + 1) {
      |         ^~~~~
      |         State
a.cc: In function 'int astat(Puzzle)':
a.cc:65:3: error: 's' was not declared in this scope
   65 |   s.MD = getAllMD(s);
      |   ^
a.cc: In function 'int main()':
a.cc:127:11: error: 'astar' was not declared in this scope; did you mean 'astat'?
  127 |   cout << astar(in) << endl;
      |           ^~~~~
      |           astat
In file included from /usr/include/c++/14/string:49,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_function.h: In instantiation of 'constexpr bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = State]':
/usr/include/c++/14/bits/predefined_ops.h:196:23:   required from 'bool __gnu_cxx::__ops::_Iter_comp_val<_Compare>::operator()(_Iterator, _Value&) [with _Iterator = __gnu_cxx::__normal_iterator<State*, std::vector<State, std::allocator<State> > >; _Value = State; _Compare = std::less<State>]'
  196 |         { return bool(_M_comp(*__it, __val)); }
      |                       ~~~~~~~^~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:140:48:   required from 'void std::__push_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare&) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<State*, vector<State, allocator<State> > >; _Distance = long int; _Tp = State; _Compare = __gnu_cxx::__ops::_Iter_comp_val<less<State> >]'
  140 |       while (__holeIndex > __topIndex && __comp(__first + __parent, __value))
      |                                          ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:216:23:   required from 'void std::push_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<State*, vector<State, allocator<State> > >; _Compare = less<State>]'
  216 |       std::__push_heap(__first, _DistanceType((__last - __first) - 1),
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  217 |                        _DistanceType(0), _GLIBCXX_MOVE(__value), __cmp);
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_queue.h:739:16:   required from 'void std::priority_queue<_Tp, _Sequence, _Compare>::push(const value_type&) [with _Tp = State; _Sequence = std::vector<State, std::allocator<State> >; _Compare = std::less<State>; value_type = State]'
  739 |         std::push_heap(c.begin(), c.end(), comp);
      |         ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:72:10:   required from here
   72 |   PQ.push(initial);
      |   ~~~~~~~^~~~~~~~~
/usr/include/c++/14/bits/stl_function.h:405:20: error: no match for 'operator<' (operand types are 'const State' and 'const State')
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
In file included from /usr/include/c++/14/string:48:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const State' is not derived from 'const std::reverse_iterator<_Iterator>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const State' is not derived from 'const std::reverse_iterator<_Iterator>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const State' is not derived from 'const std::move_iterator<_IteratorL>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_function.h:405:20: note:   'const State' is not derived from 'const std::move_iterator<_IteratorL>'
  405 |       { return __x < __y; }
      |                ~~~~^~~~~