Language: C++

#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
#include <cstring>
#include <deque>
#include <iomanip>
#include <limits>
#include <fstream>
using namespace std;
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)
#define CLR(mat) memset(mat, 0, sizeof(mat))
typedef long long ll;

//unionfind tree
struct UnionFind {
  vector<int> par;
  vector<int> rnk;
  int n;
  UnionFind(int n):n(n){
    par.resize(n);rnk.resize(n);
    for(int i=0; i<n; i++){par[i] = i;rnk[i] = 0;}
  }
  int find(int x){
      if(par[x] == x) return x;
      else return par[x] = find(par[x]);
  }
  void unite(int x, int y){
      x = find(x);y = find(y);
      if(x == y) return;
      if(rnk[x] < rnk[y])par[x] = y;
      else {
        par[y] = x;
        if(rnk[x] == rnk[y]) rnk[x]++;
      }
      return;
  }
  bool isSame(int x, int y){return find(x) == find(y);}
}

// クラスカル法(最小全域木求めるやつ)
bool comp(edge& e1, edge& e2){
  return e1.cost < e2.cost;
}
struct edge{ll u, v ; ll cost; };

int main(){
    int V,E;
    cin>>V>>E;
    vector<edge> es(E);
    FOR(i,0,E){
        cin>>es[i].u>>es[i].v>>es[i].cost;
    }
    sort(es.begin(), es.end(), comp);
    UnionFind U(V);
    ll res = 0;
    FOR(i,0,E){
        edge e = es[i];
        if(!U.isSame(e.u, e.v)){
            U.unite(e.u, e.v);
            res += e.cost;
        }
    }
    cout<<res<<endl;
    return 0;
}



Compiler output:
a.cc:49:2: error: expected ';' after struct definition
   49 | }
      |  ^
      |  ;
a.cc:52:11: error: 'edge' was not declared in this scope
   52 | bool comp(edge& e1, edge& e2){
      |           ^~~~
a.cc:52:17: error: 'e1' was not declared in this scope; did you mean 'y1'?
   52 | bool comp(edge& e1, edge& e2){
      |                 ^~
      |                 y1
a.cc:52:21: error: 'edge' was not declared in this scope
   52 | bool comp(edge& e1, edge& e2){
      |                     ^~~~
a.cc:52:27: error: 'e2' was not declared in this scope
   52 | bool comp(edge& e1, edge& e2){
      |                           ^~
a.cc:52:29: error: expression list treated as compound expression in initializer [-fpermissive]
   52 | bool comp(edge& e1, edge& e2){
      |                             ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:71,
                 from /usr/include/c++/14/algorithm:60,
                 from a.cc:1:
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'constexpr bool __gnu_cxx::__ops::_Iter_comp_iter<_Compare>::operator()(_Iterator1, _Iterator2) [with _Iterator1 = __gnu_cxx::__normal_iterator<edge*, std::vector<edge> >; _Iterator2 = __gnu_cxx::__normal_iterator<edge*, std::vector<edge> >; _Compare = bool]':
/usr/include/c++/14/bits/stl_algo.h:1777:14:   required from 'void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1777 |           if (__comp(__i, __first))
      |               ~~~~~~^~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1817:25:   required from 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1817 |           std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1908:31:   required from 'void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1908 |           std::__final_insertion_sort(__first, __last, __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:4805:18:   required from 'void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = bool]'
 4805 |       std::__sort(__first, __last, __gnu_cxx::__ops::__iter_comp_iter(__comp));
      |       ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:64:9:   required from here
   64 |     sort(es.begin(), es.end(), comp);
      |     ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h:158:30: error: expression cannot be used as a function
  158 |         { return bool(_M_comp(*__it1, *__it2)); }
      |                       ~~~~~~~^~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'bool __gnu_cxx::__ops::_Val_comp_iter<_Compare>::operator()(_Value&, _Iterator) [with _Value = edge; _Iterator = __gnu_cxx::__normal_iterator<edge*, std::vector<edge> >; _Compare = bool]':
/usr/include/c++/14/bits/stl_algo.h:1757:20:   required from 'void std::__unguarded_linear_insert(_RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Val_comp_iter<bool>]'
 1757 |       while (__comp(__val, __next))
      |              ~~~~~~^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1785:36:   required from 'void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1785 |             std::__unguarded_linear_insert(__i,
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
 1786 |                                 __gnu_cxx::__ops::__val_comp_iter(__comp));
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1817:25:   required from 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1817 |           std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1908:31:   required from 'void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1908 |           std::__final_insertion_sort(__first, __last, __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:4805:18:   required from 'void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = bool]'
 4805 |       std::__sort(__first, __last, __gnu_cxx::__ops::__iter_comp_iter(__comp));
      |       ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:64:9:   required from here
   64 |     sort(es.begin(), es.end(), comp);
      |     ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h:240:30: error: expression cannot be used as a function
  240 |         { return bool(_M_comp(__val, *__it)); }
      |                       ~~~~~~~^~~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'bool __gnu_cxx::__ops::_Iter_comp_val<_Compare>::operator()(_Iterator, _Value&) [with _Iterator = __gnu_cxx::__normal_iterator<edge*, std::vector<edge> >; _Value = edge; _Compare = bool]':
/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<edge*, vector<edge> >; _Distance = long int; _Tp = edge; _Compare = __gnu_cxx::__ops::_Iter_comp_val<bool>]'
  140 |       while (__holeIndex > __topIndex && __comp(__first + __parent, __value))
      |                                          ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:247:23:   required from 'void std::__adjust_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Distance = long int; _Tp = edge; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
  247 |       std::__push_heap(__first, __holeIndex, __topIndex,
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  248 |                        _GLIBCXX_MOVE(__value), __cmp);
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:356:22:   required from 'void std::__make_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare&) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
  356 |           std::__adjust_heap(__first, __parent, __len, _GLIBCXX_MOVE(__value),
      |           ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  357 |                              __comp);
      |                              ~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1593:23:   required from 'void std::__heap_select(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1593 |       std::__make_heap(__first, __middle, __comp);
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1868:25:   required from 'void std::__partial_sort(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1868 |       std::__heap_select(__first, __middle, __last, __comp);
      |       ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1884:27:   required from 'void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Size = long int; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1884 |               std::__partial_sort(__first, __last, __last, __comp);
      |               ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1905:25:   required from 'void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]'
 1905 |           std::__introsort_loop(__first, __last,
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
 1906 |                                 std::__lg(__last - __first) * 2,
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1907 |                                 __comp);
      |                                 ~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:4805:18:   required from 'void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = __gnu_cxx::__normal_iterator<edge*, vector<edge> >; _Compare = bool]'
 4805 |       std::__sort(__first, __last, __gnu_cxx::__ops::__iter_comp_iter(__comp));
      |       ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:64:9:   required from here
   64 |     sort(es.begin(), es.end(), comp);
      |     ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14