Submission #240210

#	Time	Username	Problem	Language	Result	Execution time	Memory
240210		aggu_01000101	Network (BOI15_net)	C++14	0 / 100	5 ms	384 KiB

net

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define int long long
#define INF 1000000000000000
#define lchild(i) (i*2 + 1)
#define rchild(i) (i*2 + 2)
#define mid(l, u) ((l+u)/2)
#define x(p) p.first
#define y(p) p.second
#define MOD 998244353
#define ordered_set tree<pair<int, int>, null_type,less<pair<int, int>>, rb_tree_tag,tree_order_statistics_node_update>
using namespace std;
map<int, int> mp;
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int n;
    cin>>n;
    for(int i =1 ;i<n;i++){
        int u, v;
        cin>>u>>v;
        mp[u]++;
        mp[v]++;
    }
    int l = 0;
    vector<int> v;
    for(int i = 1;i<=n;i++){
        l += (mp[i] == 1);
        if(mp[i] == 1) v.push_back(i);
    }
    l = (l/2) + (l%2);
    cout<<l<<"\n";
    for(int i = 1;i<v.size();i+=2){
        cout<<v[i]<<" "<<v[i-1]<<"\n";
    }
    if(v.size()%2 != 0){
        cout<<v[v.size() - 2]<<" "<<v[v.size() - 1]<<"\n";
    }
}
/*
5 4
35 100
70 70
45 15
80 40
20 95
20 50 120
10 10 100
60 60 80
0 100 100


10 10
41304 98327
91921 28251
85635 59191
30361 72671
28949 96958
99041 37826
10245 2726
19387 20282
60366 87723
95388 49726
52302 69501 66009
43754 45346 3158
25224 58881 18727
7298 24412 63782
24107 10583 61508
65025 29140 7278
36104 56758 2775
23126 67608 122051
56910 17272 62933
39675 15874 117117
 */

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:35:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 1;i<v.size();i+=2){
                   ~^~~~~~~~~

• Subtask 1: 0 / 18
• Subtask 2: 0 / 45
• Subtask 3: 0 / 37