PAT 1021. Traversal of the deep root (25 points) graph, DFS, calculating the number of connected components

1021. Deepest Root (25 branch )

#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
using namespace std;
int maxheight=0;
vector<vector<int>>v;
vector<bool>visit;
set<int>s;
vector<int>temp;
void dfs(int node,int height){
    
    visit[node]=true;
    if(height>maxheight){
    
        maxheight=height;
        temp.clear();
        temp.push_back(node);
    }else if(height==maxheight){
    
        temp.push_back(node);
    }
    for(int i=0;i<v[node].size();i++){
    
        if(visit[v[node][i]]==false)
            dfs(v[node][i],height+1);
    }
}
int main() {
    
    int n,a,b,cnt=0,s1=0;
    cin>>n;
    v.resize(n+1),visit.resize(n+1);
    for(int i=0;i<n-1;i++){
    
        cin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for(int i=1;i<=n;i++){
    
        if(visit[i]==false){
    
            dfs(i,1);
            if(i==1){
           // for the first time dfs End of traversal , Record another farthest starting point s1, And the farthest node set ;
                if(temp.size()!=0) s1=temp[0];
                for(int j=0;j<temp.size();j++)
                    s.insert(temp[j]);
            }
            cnt++;         // Connected component ++
        }
    }
    if(cnt>1) printf("Error: %d components", cnt);
    else{
    
        temp.clear();
        maxheight=0;
        fill(visit.begin(),visit.end(),false);
        dfs(s1,1);
        for(int i=0;i<temp.size();i++)
            s.insert(temp[i]);
        for(auto it=s.begin();it!=s.end();it++)
            cout<<*it<<endl;
    }
    return 0;
}