oj.uz

Submission #106889

# Submission time Handle Problem Language Result Execution time Memory
106889 2019-04-20T20:23:01 Z Pajaraja Network (BOI15_net) C++17
0 / 100
 15 ms 12032 KB 
#include <bits/stdc++.h>
using namespace std;
int cnt;
vector<int> g[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;
    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 j=0;j<l/2;j++) printf("%d %d\n",k[j],k[j+l/2]);
      	if(l%2==1) printf("%d %d",i,k[l-1]);
        return 0;
    }
}

Compilation message

net.cpp: In function 'void dfs(int, int)':
net.cpp:9:18: 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:14:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
     ~~~~~^~~~~~~~~
net.cpp:17:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&v1,&v2);
         ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 12032 KB Output is correct
2 Correct 12 ms 12032 KB Output is correct
3 Correct 15 ms 12032 KB Output is correct
4 Correct 13 ms 12032 KB Output is correct
5 Correct 14 ms 12032 KB Output is correct
6 Correct 13 ms 12032 KB Output is correct
7 Incorrect 13 ms 12032 KB Breaking single line is causing network to disconnect.
8 Halted 0 ms 0 KB -

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 12032 KB Output is correct
2 Correct 12 ms 12032 KB Output is correct
3 Correct 15 ms 12032 KB Output is correct
4 Correct 13 ms 12032 KB Output is correct
5 Correct 14 ms 12032 KB Output is correct
6 Correct 13 ms 12032 KB Output is correct
7 Incorrect 13 ms 12032 KB Breaking single line is causing network to disconnect.
8 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 12032 KB Output is correct
2 Correct 12 ms 12032 KB Output is correct
3 Correct 15 ms 12032 KB Output is correct
4 Correct 13 ms 12032 KB Output is correct
5 Correct 14 ms 12032 KB Output is correct
6 Correct 13 ms 12032 KB Output is correct
7 Incorrect 13 ms 12032 KB Breaking single line is causing network to disconnect.
8 Halted 0 ms 0 KB -