Submission #24944

#	Time	Username	Problem	Language	Result	Execution time	Memory
24944		RezwanArefin01	Network (BOI15_net)	C++14	100 / 100	623 ms	42508 KiB

net

//Bismillahir Rahmanir Rahim
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> ii;
const int maxn = 5e5;
vector<int> adj[maxn], lef; 
void dfs(int u, int par){
	for(int v : adj[u]) if(v - par) dfs(v, u);
	if(adj[u].size() == 1) lef.push_back(u);
}
int main(int argc, char const *argv[]) {
#ifdef LOCAL_TESTING
	freopen("in", "r", stdin);
#endif
	int n; scanf("%d", &n);
	for(int i=0; i<n-1; i++) {
		int u, v; 
		scanf("%d %d", &u, &v);
		adj[u].push_back(v); 
		adj[v].push_back(u); 
	}
	for(int i=1; i<=n; i++) if(adj[i].size() > 1) {
		dfs(i, 0); break;
	}
	int sz = int((lef.size()+1)/2); 
	printf("%d\n", sz);
	for(int i=0; i<sz; i++) {
		printf("%d %d\n", lef[i], lef[i + lef.size()/2]);
	}
} 

Compilation message (stderr)

net.cpp: In function 'int main(int, const char**)':
net.cpp:16:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  int n; scanf("%d", &n);
                        ^
net.cpp:19:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &u, &v);
                         ^

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