Submission #106883

#	Time	Username	Problem	Language	Result	Execution time	Memory
106883		Pajaraja	Network (BOI15_net)	C++17	Compilation error	0 ms	0 KiB

net

#include <bits/stdc++.h>
using namespace std;
int cnt,nes;
vector<int> g[500007],d[500007];
vector<bool> v[500007];
int k[500007];
void dfs(int s,int f)
{
    if(g[s].size()==1)
    {
        k[cnt++]=s;
        return;
    }
    for(int i=0;i<g[s].size();i++) if(g[s][i]!=f) dfs(g[s][i],s);
}
int main()
{
    int n,v1,v2,l=0;
    nes=0;
    fill(k,k+200007,0);
    scanf("%d",&n);
    for(int i=0;i<n-1;i++)
    {
        scanf("%d%d",&v1,&v2);
        g[v1].push_back(v2);
        g[v2].push_back(v1);
    }
    for(int i=1;i<=n;i++) if(g[i].size()==1) l++;
    printf("%d\n",(l+1)/2);
    for(int i=1;i<=n;i++) if(g[i].size()>1)
    {
        dfs(i,0);
      	for(int i=0;i<l/2;i++) printf("%d %d\n",k[i],k[i+l/2]);
      	if(l%2==0) printf("%d %d",s,k[l-1]);
        return 0;
    }
}

Compilation message (stderr)

net.cpp: In function 'void dfs(int, int)':
net.cpp:14:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<g[s].size();i++) if(g[s][i]!=f) dfs(g[s][i],s);
                 ~^~~~~~~~~~~~
net.cpp: In function 'int main()':
net.cpp:34:34: error: 's' was not declared in this scope
        if(l%2==0) printf("%d %d",s,k[l-1]);
                                  ^
net.cpp:21:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
net.cpp:24:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&v1,&v2);
         ~~~~~^~~~~~~~~~~~~~~~