Submission #134329

#	Time	Username	Problem	Language	Result	Execution time	Memory
134329		Kastanda	Network (BOI15_net)	C++11	100 / 100	611 ms	57800 KiB

net

// ItnoE
#include<bits/stdc++.h>
using namespace std;
const int N = 500005;
int n;
vector < int > V, Adj[N];
void DFS(int v, int p)
{
    for (int &u : Adj[v])
        if (u != p)
            DFS(u, v);
    if (Adj[v].size() == 1)
        V.push_back(v);
}
int main()
{
    scanf("%d", &n);
    for (int i = 1; i < n; i ++)
    {
        int v, u;
        scanf("%d%d", &v, &u);
        Adj[v].push_back(u);
        Adj[u].push_back(v);
    }
    int root = 1;
    for (int i = 1; i <= n; i ++)
        if (Adj[i].size() > 1)
            root = i;
    DFS(root, 0);
    printf("%d\n", (int)(V.size() + 1) / 2);
    for (int i = 0; i < (V.size() + 1) / 2; i ++)
        printf("%d %d\n", V[i], V[i + (int)V.size() / 2]);
    return 0;
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < (V.size() + 1) / 2; i ++)
                     ~~^~~~~~~~~~~~~~~~~~~~
net.cpp:17:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
net.cpp:21:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &v, &u);
         ~~~~~^~~~~~~~~~~~~~~~

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