Language: C++

#include<iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <tuple>
#include <cmath>
#include <queue>
#include <map>

#define ll int64_t
using namespace std;
const long MOD = 1e9 + 7;
const ll INF = 1LL << 60;

void dfs(int from,int node, int value, bool isOdd);


vector< pair< ll, ll > > Graph[100001]; //G[ノード数]:{pair<辺の距離, 行き先の頂点>}
vector< vector < pair< ll, bool > > > v(100001); //各ノードにおける結果

bool isFalse = false;
bool isodd=false;

vector<bool> oddval(100001, false);//２つでセット：奇数距離ノードと偶数距離ノードが同一のときの判定に利用
vector<ll> oddvalue(100001, 0);


vector<bool> isusedNode(100001,false);




int main()
{
  int N, M, S, T;
  cin >> N >> M;
  long u1, v1, s;

  for (int i = 0; i < M; i++) {//アーク数
    cin >> u1 >> v1 >> s;
    Graph[u1 - 1].push_back(make_pair(s, v1 - 1)); //グラフのノードu1-1にコストs,行き先v1-1のパスを追加する
    Graph[v1 - 1].push_back(make_pair(s, u1 - 1)); //グラフのノードv1-1にコストs,行き先u1-1のパスを追加する
  }

  ll UB = INF;
  ll LB = 0;


  dfs(0,0, 0, false);

  for (int i = 0; i < v.size(); i++) {
    for (int  j = 0; j < v[i].size(); j++) {
      if (v[i][j].second == true) { //偶数距離
        if (UB > v[i][j].first)UB = v[i][j].first;
      } else { //奇数距離
        if (LB < v[i][j].first)LB = v[i][j].first;
      }
       // cout << v[i][j].first << endl;
      //cout << "   value:"<< v[i][j].first<< "  isOdd:" << v[i][j].second<< endl;

    }
  }

  if (isFalse == true) {//ループがあり実行不可のとき
    cout << "1" <<endl;
  }else if(isodd==true){//ループがあり、なおかつ実行可能なとき
    cout << "0" <<endl;
  }else{
    cout << max<ll>(0, (UB - 1)  - (LB + 1) + 1 ) << endl;
  }

  // cout << UB << ":U:L:" << LB << endl;


  return 0;
}


void dfs(int from,int node, int value, bool isOdd) { //一個目がノードで２個めが値
  //cout << "node:" << node << "   value:"<< value<< "  isOdd:" << isOdd<< endl;

  // for (int i = 0; i < Graph[node].size(); i++) {
  //   cout << Graph[node][i].second << " -";
  // } cout << endl;
  if (isFalse ==true) return;
  if (v[node].size() > 0 ) {//既に到着しているとき
    for (int i = 0; i < v[node].size(); i++) {
      if (v[node][i].second == isOdd ) { //距離一致するとき
        if (v[node][i].first != value)isFalse = true;
      } else { //距離一致しないとき
        isodd=true;
        if (
        [node]==false) {//2つの一致のとき
          oddval[node] = true;
          oddvalue[node] = (value - v[node][i].first ) / 2;
        } else {
          if (oddvalue[node] != (value - v[node][i].first ) / 2)isFalse = true;
        }
      }
    }
    return ;
  }

  v[node].push_back(make_pair(value, isOdd));
  for (int i = 0; i < Graph[node].size(); i++) {
    ll tn = Graph[node][i].second;
    ll ecost = Graph[node][i].first;
    if (tn==from)continue;
    if (isOdd)dfs(node,tn, value - ecost, !isOdd);
    if (!isOdd)dfs(node,tn, value + ecost, !isOdd);
  }

}



Compiler output:
a.cc: In lambda function:
a.cc:93:15: error: expected '{' before '==' token
   93 |         [node]==false) {//2つの一致のとき
      |               ^~
a.cc: In function 'void dfs(int, int, int, bool)':
a.cc:93:15: error: no match for 'operator==' (operand types are 'dfs(int, int, int, bool)::<lambda()>' and 'bool')
   93 |         [node]==false) {//2つの一致のとき
      |         ~~~~~~^~~~~~~
In file included from /usr/include/c++/14/iosfwd:42,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/postypes.h:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::fpos<_StateT>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
In file included from /usr/include/c++/14/string:43,
                 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:
/usr/include/c++/14/bits/allocator.h:235:5: note: candidate: 'template<class _T1, class _T2> bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)'
  235 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:235:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::allocator<_CharT>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
In file included from /usr/include/c++/14/string:48:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::reverse_iterator<_Iterator>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::reverse_iterator<_Iterator>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::move_iterator<_IteratorL>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::move_iterator<_IteratorL>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/string:51:
/usr/include/c++/14/bits/stl_pair.h:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::pair<_T1, _T2>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/usr/include/c++/14/string_view:629:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  629 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:629:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
/usr/include/c++/14/string_view:637:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  637 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:637:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
/usr/include/c++/14/string_view:644:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  644 |     operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:644:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'bool'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
/usr/include/c++/14/bits/basic_string.h:3755:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3755 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3755:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
/usr/include/c++/14/bits/basic_string.h:3772:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3772 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3772:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
/usr/include/c++/14/bits/basic_string.h:3819:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3819 |     operator==(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3819:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   mismatched types 'const _CharT*' and 'dfs(int, int, int, bool)::<lambda()>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68:
/usr/include/c++/14/tuple:2558:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std::operator==(const tuple<_UTypes ...>&, const tuple<_Elements ...>&)'
 2558 |     operator==(const tuple<_TElements...>& __t,
      |     ^~~~~~~~
/usr/include/c++/14/tuple:2558:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bool)::<lambda()>' is not derived from 'const std::tuple<_UTypes ...>'
   93 |         [node]==false) {//2つの一致のとき
      |                 ^~~~~
In file included from /usr/include/c++/14/bits/locale_facets.h:48,
                 from /usr/include/c++/14/bits/basic_ios.h:37,
                 from /usr/include/c++/14/ios:46:
/usr/include/c++/14/bits/streambuf_iterator.h:234:5: note: candidate: 'template<class _CharT, class _Traits> bool std::operator==(const istreambuf_iterator<_CharT, _Traits>&, const istreambuf_iterator<_CharT, _Traits>&)'
  234 |     operator==(const istreambuf_iterator<_CharT, _Traits>& __a,
      |     ^~~~~~~~
/usr/include/c++/14/bits/streambuf_iterator.h:234:5: note:   template argument deduction/substitution failed:
a.cc:93:17: note:   'dfs(int, int, int, bo