Submission #588562

#	Time	Username	Problem	Language	Result	Execution time	Memory
588562		M_W	Network (BOI15_net)	C++17	0 / 100	1 ms	312 KiB

net

#include <bits/stdc++.h>
using namespace std;
vector<int> v;
int deg[500001];
int main(){
	int N;
	scanf("%d", &N);
	for(int i = 1, u, v; i < N; i++){
		scanf("%d %d", &u, &v);
		deg[u]++; deg[v]++;
	}
	for(int i = 1; i <= N; i++){
		if(deg[i] == 1) v.push_back(i);
	}
	queue<pair<int, int>> q;
	for(int i = 0; i + 1 < v.size(); i += 2){
		q.push({v[i], v[i + 1]});
	}
	if(v.size() % 2) q.push({v[v.size() - 1], 0});
	printf("%d\n", q.size());
	while(!q.empty()){
		printf("%d %d\n", q.front().first, q.front().second);
		q.pop();
	}
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:16:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |  for(int i = 0; i + 1 < v.size(); i += 2){
      |                 ~~~~~~^~~~~~~~~~
net.cpp:20:11: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::queue<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wformat=]
   20 |  printf("%d\n", q.size());
      |          ~^     ~~~~~~~~
      |           |           |
      |           int         std::queue<std::pair<int, int> >::size_type {aka long unsigned int}
      |          %ld
net.cpp:7:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
    7 |  scanf("%d", &N);
      |  ~~~~~^~~~~~~~~~
net.cpp:9:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
    9 |   scanf("%d %d", &u, &v);
      |   ~~~~~^~~~~~~~~~~~~~~~~

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