Submission #83443

#	Time	Username	Problem	Language	Result	Execution time	Memory
83443		nikolapesic2802	Network (BOI15_net)	C++14	100 / 100	668 ms	153300 KiB

net

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define ll long long
#define pb push_back

using namespace std;
using namespace __gnu_pbds;

typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set; ///find_by_order(),order_of_key()

const int N=500005;
vector<vector<int> > graf(N);
vector<int> leaves;

void dfs(int tr,int par)
{
    if(graf[tr].size()==1)
        leaves.pb(tr);
    for(auto p:graf[tr])
    {
        if(p==par)
            continue;
        dfs(p,tr);
    }
}
int main()
{
    int n;
    scanf("%i",&n);
    for(int i=1;i<n;i++)
    {
        int a,b;
        scanf("%i %i",&a,&b);
        graf[a].pb(b);
        graf[b].pb(a);
    }
    dfs(1,-1);
    int t=leaves.size()/2;
    printf("%i\n",(leaves.size()+1)/2);
    for(int i=0;i<(leaves.size()+1)/2;i++)
    {
        printf("%i %i\n",leaves[i],leaves[i+t]);
    }
    return 0;
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:41:38: warning: format '%i' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type {aka long unsigned int}' [-Wformat=]
     printf("%i\n",(leaves.size()+1)/2);
                   ~~~~~~~~~~~~~~~~~~~^
net.cpp:42:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<(leaves.size()+1)/2;i++)
                 ~^~~~~~~~~~~~~~~~~~~~
net.cpp:31:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%i",&n);
     ~~~~~^~~~~~~~~
net.cpp:35:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%i %i",&a,&b);
         ~~~~~^~~~~~~~~~~~~~~

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