Language: C++

#include <bits/stdc++.h>
 
using namespace std;
 
const int MOD=1e9+7;
const double PI=3.14159265359;


int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    int n,m;
    cin>>n>>m;
    
    vector<vector<pair<int,int>>> graph(n+1);
    
    for(int i=0; i<m; i++){
        int x,y,s;
        cin>>x>>y>>s;
        graph[x].push_back({y,s});
        graph[y].push_back({x,s});
    }
    
    
    if(m==n-1){
        vector<long long> dists(n+1,-1), vals(n+1);
        
        
        long long minev=1e10, minov=1e10;
        
        vals[1]=1;
        dists[1]=0;
        
        queue<int> q;
        q.push(1);
        
        while(q.size()){
            int cur=q.front();
            q.pop();
            
            for(auto p: graph[cur]){
                if(dists[p.first]==-1){
                    q.push(p.first);
                    dists[p.first]=dists[cur]+1;
                    
                    vals[p.first]=p.second-vals[cur];
                    
                    if(dists[p.first]%2){
                        minov=min(minov, vals[p.first]);
                    }
                    else{
                        minev=min(minev, vals[p.first]);
                        
                    }
                }
            }
            
        }
        
        /*
        for(int i=1; i<=n; i++){
            cout<<vals[i]<<" ";
        }
        */
        
        if(minev<0){
            minov+=minev-1;
        }
        
        cout<<max(0ll, minov);
        return 0;
        
        
        
    }
    
    //cout<<1;
    

 
    vector<int> preds(n+1,-1);
    stack<int> st;
    preds[1]=1;
    st.push(1);
    
    vector<int> cycle;
    
    bool cyf=false;
    while(st.size()){
        int cur=st.top();
        for(auto p:graph[cur]){
            if(p.first!=preds[cur]){
                if(preds[p.first]==-1){
                    st.push(p.first);
                }
                else if(!cyf){
                    int cur2=cur;
                    while(cur2!=p.first){
                        //cout<<cur2<<endl;
                        cycle.push_back(cur2);
                        cur2=preds[cur2];
                    }
                    cycle.push_back(p.first);
                    cyf=true;
                    
                }
            }
        }
        if(st.top()==cur) st.pop();
        else preds[st.top()]=cur;
        
    }
    
    /*
    for(int i:cycle){
        cout<<i<<" ";
    }
    cout<<endl;
    
    
    int sz=cycle.size();
    vector<int> s(sz);
    for(int i=0; i<sz; i++){
        
        int goal=cycle[(i+1)%sz];
        
        
        
        for(auto p:graph[cycle[i]]){
            if(p.first==goal){
                s[i]=p.second;
                break;
            }
        }
        //cout<<i<<" "<<cycle[i]<<" "<<goal<<" "<<s[i]<<endl;
        
    }

    
    if(sz%2){
        
        /*
        for(int i:s){
            cout<<i<<" ";
        }
        */
        vector<long long> vals(n+1);
        
        long long sum=0;
        for(int i=0; i<sz; i++){
            sum+=(i%2?-1*s[i]:s[i]);
        }
        //cout<<sum;
        
        if(sum%2 || sum<1){
            cout<<0;
            return 0;
        }
        
        vals[cycle[0]]=sum/2;
        
        
        vector<bool> visited(n+1);
        visited[cycle[0]]=1;
        
        
        queue<int> q;
        
        q.push(cycle[0]);
        
        while(q.size()){
            int cur=q.front();
            q.pop();
            
            for(auto p: graph[cur]){
                if(!visited[p.first]){
                    q.push(p.first);
                    visited[p.first]=1;
                    vals[p.first]=p.second-vals[cur];
                }
            }
            
        }
        
        /*
        for(int i=1; i<=n; i++){
            cout<<vals[i]<<" ";
        }
        cout<<endl;
        */
        
        for(int i=1; i<=n; i++){
            if(vals[i]<1){
                cout<<0;
                return 0;
            }
            for(auto p:graph[i]){
                if(vals[p.first]+vals[i]!=p.second){
                    cout<<0;
                    return 0;
                }
            }
        }
        
        cout<<1;
        return 0;
        
    }
    
    long long sum=0;
    for(int i=0; i<sz; i++){
        sum+=(i%2?-1*s[i]:s[i]);
    }
    cout<<!sum;
    
*/

cout<<0
    
   
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:151:24: error: 'sz' was not declared in this scope; did you mean 'st'?
  151 |         for(int i=0; i<sz; i++){
      |                        ^~
      |                        st
a.cc:152:26: error: 's' was not declared in this scope
  152 |             sum+=(i%2?-1*s[i]:s[i]);
      |                          ^
a.cc: At global scope:
a.cc:212:5: error: expected unqualified-id before 'for'
  212 |     for(int i=0; i<sz; i++){
      |     ^~~
a.cc:212:18: error: 'i' does not name a type
  212 |     for(int i=0; i<sz; i++){
      |                  ^
a.cc:212:24: error: 'i' does not name a type
  212 |     for(int i=0; i<sz; i++){
      |                        ^
a.cc:215:5: error: 'cout' does not name a type
  215 |     cout<<!sum;
      |     ^~~~
a.cc:217:2: error: expected unqualified-id before '/' token
  217 | */
      |  ^
a.cc:223:1: error: expected declaration before '}' token
  223 | }
      | ^