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Submission #305449

# Submission time Handle Problem Language Result Execution time Memory
305449 2020-09-23T08:21:30 Z shahriarkhan Network (BOI15_net) C++14
0 / 100
 10 ms 12032 KB 
#include<bits/stdc++.h>
using namespace std ;

const int siz = 5e5 + 69 ;

vector<int> adj[siz] ;

int col[siz] ;

void dfs(int s , int p)
{
    for(int t : adj[s])
    {
        if(t==p) continue ;
        dfs(t,s) ;
        col[t] = col[s] ;
    }
}

int main()
{
    int n ;
    scanf("%d",&n) ;
    int deg[n+1] = {0} , mx = 0 , root = 0 ;
    for(int i = 1 ; i < n ; ++i)
    {
        int u , v ;
        scanf("%d%d",&u,&v) ;
        adj[u].push_back(v) ;
        adj[v].push_back(u) ;
        ++deg[u] , ++deg[v] ;
        mx = max(mx,max(deg[u],deg[v])) ;
    }
    for(int i = 1 ; i <= n ; ++i)
    {
        if(deg[i]==mx)
        {
            root = i ;
            break ;
        }
    }
    int cnt = 0 , cur = 1 ;
    for(int i : adj[root])
    {
        col[i] = ++cnt ;
        dfs(i,root) ;
    }
    vector<pair<int,int> > ar ;
    for(int i = 1 ; i <= n ; ++i)
    {
        if(deg[i]==1)
        {
            ar.push_back({col[i],i}) ;
        }
    }
    int six = ar.size() ;
    sort(ar.begin(),ar.end()) ;
    if(six%2)
    {
        ar.push_back(ar[0]) ;
        ++six ;
    }
    printf("%d\n",(six+1)/2) ;
    for(int i = 0 ; i < six ; i += 2)
    {
        printf("%d %d\n",ar[i].second,ar[i+1].second) ;
    }
    return 0 ;
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:42:19: warning: unused variable 'cur' [-Wunused-variable]
   42 |     int cnt = 0 , cur = 1 ;
      |                   ^~~
net.cpp:23:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   23 |     scanf("%d",&n) ;
      |     ~~~~~^~~~~~~~~
net.cpp:28:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   28 |         scanf("%d%d",&u,&v) ;
      |         ~~~~~^~~~~~~~~~~~~~

Subtask #1
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Incorrect 10 ms 12032 KB Breaking single line is causing network to disconnect.
3 Halted 0 ms 0 KB -

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Incorrect 10 ms 12032 KB Breaking single line is causing network to disconnect.
3 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Incorrect 10 ms 12032 KB Breaking single line is causing network to disconnect.
3 Halted 0 ms 0 KB -