Submission #113182

#	Time	Username	Problem	Language	Result	Execution time	Memory
113182		davitmarg	Network (BOI15_net)	C++17	0 / 100	4 ms	2688 KiB

net

/*DavitMarg*/
#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <queue>
#include <iomanip>
#include <bitset>
#include <stack>
#include <cassert>
#include <iterator>
#include <ctype.h>
#include <fstream>
#define mod 1000000007ll
#define LL long long
#define LD long double
#define MP make_pair
#define PB push_back
#define all(v) v.begin (),v.end()
using namespace std;

int n;
vector<int> g[100005],t;
vector<pair<int, int>> ans;
int main()
{
	cin >> n;
	if (n == 0)
	{
		printf("0\n");
		return 0;
	}
	for (int i = 1; i < n; i++)
	{
		int a, b;
		scanf("%d%d", &a, &b);
		g[a].PB(b);
		g[b].PB(a);
	}
	for (int i = 1; i <= n; i++)
		if (g[i].size() == 1)
			t.PB(i);
	random_shuffle(all(t));
	if (t.size() % 2)
		ans.PB(MP(t[t.size() - 2], t.back()));
	for (int i = 1; i < t.size(); i += 2)
		ans.PB(MP(t[i - 1], t[i]));

	printf("%d\n",(int)ans.size());
	for (int i = 0; i < ans.size(); i++)
		printf("%d %d\n", ans[i].first, ans[i].second);

	return 0;
}

/*



*/

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:50:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 1; i < t.size(); i += 2)
                  ~~^~~~~~~~~~
net.cpp:54:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < ans.size(); i++)
                  ~~^~~~~~~~~~~~
net.cpp:40:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &a, &b);
   ~~~~~^~~~~~~~~~~~~~~~

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