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Submission #146831

# Submission time Handle Problem Language Result Execution time Memory
146831 2019-08-26T10:50:11 Z muhammad_hokimiyon Network (BOI15_net) C++14
0 / 100
 6 ms 5112 KB 
#include <bits/stdc++.h>
//#pragma GCC optimize("Ofast")

#define LL long long
#define se second
#define fi first

using namespace std;

const int N = 2e5 + 7;
const int mod = 1e9 + 7;
const int B = sqrt(N);

int n;
bool used[N];
vector < int > v[N];
vector < int > ans;

void dfs( int x , int p )
{
    if( v[x].size() == 1 && !used[x] ){
        ans.push_back(x);
    }
    used[x] = true;
    for( auto y : v[x] ){
        if( y == p )continue;
        dfs(y , x);
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    //freopen( "input.txt" , "r" , stdin );
    //freopen( "output.txt" , "w" , stdout );

    cin >> n;
    for( int i = 1; i < n; i++ ){
        int x,y;
        cin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for( int i = 1; i <= n; i++ ){
        if( v[i].size() > 1 ){
            dfs(i , i);
        }
    }
    int k = (ans.size() + 1) / 2;
    cout << ( (int)ans.size() + 1 ) / 2 << "\n";
    for( int i = 0; i < ( ans.size() + 1) / 2; i++ ){
        cout << ans[i] << " " << ans[ (i + k) ] << "\n";
    }
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:52:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for( int i = 0; i < ( ans.size() + 1) / 2; i++ ){
                     ~~^~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5112 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Incorrect 6 ms 5112 KB Integer 0 violates the range [1, 10]
5 Halted 0 ms 0 KB -

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5112 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Incorrect 6 ms 5112 KB Integer 0 violates the range [1, 10]
5 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5112 KB Output is correct
2 Correct 6 ms 5112 KB Output is correct
3 Correct 6 ms 5112 KB Output is correct
4 Incorrect 6 ms 5112 KB Integer 0 violates the range [1, 10]
5 Halted 0 ms 0 KB -