Submission #969438

#	Time	Username	Problem	Language	Result	Execution time	Memory
969438		vjudge1	Cities (BOI16_cities)	C++17	0 / 100	4 ms	5212 KiB

cities

#include<iostream>
#include<vector>
using namespace std;

int parent[100007];
int ans;
int u,v;
vector<int> vec[100007];
void dfs(int x,int ori)
{
    // cout << x << ' ';
    for(auto i:vec[x]){
        if(i==ori) continue;
        dfs(i,x);
    }
    if(parent[x]==x){
        ans+=2;
        if(ori) swap(parent[x],parent[ori]);
        else {
            swap(parent[x],parent[vec[x][0]]);
            // cout << x <<  ' ' << vec[x][0];
        }
    }
}
int main()
{
    int n; cin >> n;
    for(int i=1;i<n;++i){
        cin >> u >> v;
        vec[u].push_back(v);
        vec[v].push_back(u);
    }
    for(int i=1;i<=n;++i) parent[i]=i;
    dfs(1,0);
    // cout << '\n';
    cout << ans << endl;
    for(int i=1;i<=n;i++) cout << parent[i] << " ";
}

/*
5
1 2
2 3
3 4
4 5
*/

• Subtask 1: 0 / 22
• Subtask 2: 0 / 14
• Subtask 3: 0 / 15
• Subtask 4: 0 / 23
• Subtask 5: 0 / 26