Submission #335635

#	Time	Username	Problem	Language	Result	Execution time	Memory
335635		Joshc	Network (BOI15_net)	C++11	100 / 100	542 ms	52328 KiB

net

#include <cstdio>
#include <vector>
using namespace std;

vector<int> edges[500001], l;

void dfs(int v, int p) {
    if (edges[v].size() == 1) l.push_back(v);
    for (int u : edges[v]) {
        if (u != p) dfs(u, v);
    }
}

int main() {
    int n, a, b;
    scanf("%d", &n);
    for (int i=1; i<n; i++) {
        scanf("%d%d", &a, &b);
        edges[a].push_back(b);
        edges[b].push_back(a);
    }
    dfs(1, 0);
    int s = (l.size()+1)>>1;
    printf("%d\n", s);
    for (int i=0; i<s; i++) printf("%d %d\n", l[i], l[(i+s)%l.size()]);
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:16:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   16 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
net.cpp:18:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   18 |         scanf("%d%d", &a, &b);
      |         ~~~~~^~~~~~~~~~~~~~~~

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