Submission #394614

#	Time	Username	Problem	Language	Result	Execution time	Memory
394614		iANikzad	Network (BOI15_net)	C++14	100 / 100	485 ms	45248 KiB

net

#include<bits/stdc++.h>

using namespace std;

#define pb push_back
#define F first
#define S second
#define debug(x) cerr<<#x<<" :"<<x<<"\n"
#define all(x) x.begin(),x.end()
//#define pii pair<int,int>
#define FAST ios_base::sync_with_stdio(false), cin.tie(), cout.tie();
//#define int long long

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;

const int maxn = 5e5 + 7;
const int mod = 1e9 + 7;
const int INF = 1e9 + 7;
const int mlog = 20;
const int SQ = 400;

int root;

vector<int> adj[maxn];
vector<int> Leaf;

void dfs(int v,int par = -1)
{
    if(adj[v].size() == 1) Leaf.pb(v);
    for(int u : adj[v]) if(u != par) dfs(u, v);
}

int main()
{
    FAST;

    int n;
    cin >> n;

    for(int i = 1; i < n; i++)
    {
        int u, v;
        cin >> u >> v;

        adj[u].pb(v); adj[v].pb(u);
    }

    root = 1;
    dfs(root);


    int SZ = (Leaf.size() + 1) >> 1;
    cout << SZ << "\n";

    for(int i = 0; i < SZ; i++)
        cout << Leaf[i] << " " << Leaf[(i + SZ) % Leaf.size()] << "\n";

    return 0;
}

• Subtask 1: 18 / 18
• Subtask 2: 45 / 45
• Subtask 3: 37 / 37