Submission #520162

#	Time	Username	Problem	Language	Result	Execution time	Memory
520162		krit3379	Network (BOI15_net)	C++14	100 / 100	449 ms	47556 KiB

net

#include<bits/stdc++.h>
using namespace std;
#define N 500005

vector<int> g[N],v;

void dfs(int s,int f){
    if(g[s].size()==1)v.push_back(s);
    for(auto x:g[s]){
        if(x==f)continue;
        dfs(x,s);
    }
}

int main(){
    int n,i,a,b,ans;
    scanf("%d",&n);
    for(i=1;i<n;i++){
        scanf("%d %d",&a,&b);
        g[a].push_back(b);
        g[b].push_back(a);
    }
    dfs(1,0);
    printf("%d\n",ans=(v.size()+1)/2);
    for(i=0;i<ans;i++)printf("%d %d\n",v[i],(i+ans<v.size())?v[i+ans]:v[0]);
    return 0;
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:25:51: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |     for(i=0;i<ans;i++)printf("%d %d\n",v[i],(i+ans<v.size())?v[i+ans]:v[0]);
      |                                              ~~~~~^~~~~~~~~
net.cpp:17:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
net.cpp:19:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |         scanf("%d %d",&a,&b);
      |         ~~~~~^~~~~~~~~~~~~~~

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