Submission #127034

#	Time	Username	Problem	Language	Result	Execution time	Memory
127034		TadijaSebez	Network (BOI15_net)	C++11	100 / 100	573 ms	47844 KiB

net

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
const int N=500050;
vector<int> E[N],leaf;
void DFS(int u, int p)
{
	if(E[u].size()==1) leaf.pb(u);
	for(int v:E[u]) if(v!=p) DFS(v,u);
}
int main()
{
	int n,u,v;
	scanf("%i",&n);
	for(int i=1;i<n;i++) scanf("%i %i",&u,&v),E[u].pb(v),E[v].pb(u);
	DFS(1,0);
	int sz=leaf.size()+1>>1,add=leaf.size()>>1;
	printf("%i\n",sz);
	for(int i=0;i<sz;i++) printf("%i %i\n",leaf[i],leaf[i+add]);
	return 0;
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:17:20: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int sz=leaf.size()+1>>1,add=leaf.size()>>1;
         ~~~~~~~~~~~^~
net.cpp:14:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%i",&n);
  ~~~~~^~~~~~~~~
net.cpp:15:54: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1;i<n;i++) scanf("%i %i",&u,&v),E[u].pb(v),E[v].pb(u);
                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~

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