Submission #134599

#	Time	Username	Problem	Language	Result	Execution time	Memory
134599		Ace	Network (BOI15_net)	C++14	0 / 100	2 ms	380 KiB

net

#include<bits/stdc++.h>
using namespace std;

const int N = 5e5;

int n;
int ada[N+5];

int main(){
	scanf("%d",&n);
	for(int i=1;i<n;i++){
		int u,v;
		scanf("%d%d",&u,&v);
		ada[u]++;
		ada[v]++;
	}
	int cnt = 0;
	for(int i=1;i<=n;i++){
		if(ada[i] == 1) cnt++;
	}
	printf("%d\n",(cnt+1)/2);
	int tmp = -1;
	int bef = -1;
	for(int i=1;i<=n;i++){
		if(ada[i] == 1){
			if(tmp == -1) tmp = i;
			if(bef == -1){
				bef = i;
			} else {
				printf("%d %d\n",i,bef);
				bef = -1;
			}
		}
	}
	if(bef!=-1){
		printf("%d %d\n",bef,tmp);
	}
	return 0;
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:10:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
net.cpp:13:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&u,&v);
   ~~~~~^~~~~~~~~~~~~~

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