Submission #1270655

#	Time	Username	Problem	Language	Result	Execution time	Memory
1270655		raymoo_	Network (BOI15_net)	C++17	100 / 100	393 ms	49636 KiB

net

#include<bits/stdc++.h>
using namespace std; 
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define umap unordered_map
#define prq priority_queue
#define vect vector
#define rs resize
#define bend(v) v.begin(),v.end()
#define pob pop_back
#define pof pop_front
#define lwb lower_bound
#define upb upper_bound
#define pii pair<int,int>
#define nextl cout << '\n'
#define el '\n'
#define deb cout<<"\nok\n";return 
#define ll long long
#define int long long
#define dbl long double
#define popcnt __builtin_popcount
#define ctz __builtin_ctz
#define FILE "ellencute"
 
const ll INF=902337203695775807, N=5e5+69, MOD=1e9+7;    
 
void ffopen(){
    if(fopen(FILE".inp", "r")){
        freopen(FILE".inp", "r", stdin);
        freopen(FILE".out", "w", stdout);
    }else if(fopen("ellencute.inp", "r")){
        freopen("ellencute.inp", "r", stdin);
        freopen("ellencute.out", "w", stdout);
    }
}

int pm(int a,const int b=1e9+7){return ((a%b)+b)%b;}
int sq(int x){return x*x;}
ll __lcm(ll a, ll b, const ll lim=LLONG_MAX){
    if(a == -1 || b == -1)return -1;
    ll g = __gcd(a,b);
    if(b/g > lim/a)return -1;
    return (a/g)*b;
}

deque<int> ans;
vect<int> G[N], visited(N), dep(N);

void DFS(int u){
    visited[u] = 1;
    bool ok = 1;
    for(int v : G[u]) if(!visited[v]) {
        ok = 0;
        dep[v] = dep[u]+1;
        DFS(v);
    }
    if(ok) ans.eb(u);
}

void sol(){
    int n;
    cin >> n;
    for(int i=1;n>i;i++){
        int u, v;cin >> u >> v;
        G[u].eb(v);
        G[v].eb(u);
    }

    int root ;

    for(int i=1;n>=i;i++){
        if(G[i].size()>1){
            root = i;
            DFS(i);
            break;
        }
    }

    // sort(bend(ans), [](int u, int v){
    //     return dep[u] < dep[v];
    // });


    cout << (ans.size()+1)/2 << el;
        vect<int> o, e;
        for(int i=0;(ans.size()+1)/2>i;i++){
            cout << ans[i] << ' ' << ans[(i+(ans.size()+1)/2)%ans.size()] << el;
        }
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ffopen();
    int t=1;
    //cin >> t;
    while(t--)sol();
}
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*/

Compilation message (stderr)

net.cpp: In function 'void ffopen()':
net.cpp:31:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |         freopen(FILE".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:32:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |         freopen(FILE".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:34:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |         freopen("ellencute.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:35:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |         freopen("ellencute.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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