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Submission #625291

# Submission time Handle Problem Language Result Execution time Memory
625291 2022-08-09T22:06:05 Z chonka Network (BOI15_net) C++17
100 / 100
 632 ms 60268 KB 
#include<bits/stdc++.h>
using namespace std ;
typedef long long ll ;
typedef unsigned long long ull ;
#define fi first
#define se second
// mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

const int MAXN = 5e5 + 7 ;

int n ;
vector < int > v[ MAXN ] , ord ;
int cnt[ MAXN ] , root , prv[ MAXN ] ;
int spec ;

void init ( int x , int lst ) {
    bool leaf = true ;
    cnt[ x ] = 0 ;
    for ( auto y : v[ x ] ) {
        if ( y == lst ) { continue ; }
        leaf = false ;
        prv[ y ] = x ;
        init ( y , x ) ;
        cnt[ x ] += cnt[ y ] ;
    }
    if ( leaf == true ) {
        ++ cnt[ x ] ;
    }    
}

int get_centroid ( int x , int lst , int targ ) {
    for ( auto y : v[ x ] ) {
        if ( y == lst ) { continue ; }
        if ( cnt[ y ] >= targ ) {
            return get_centroid ( y , x , targ ) ;
        }
    }
    return x ;
}

void dfs ( int x , int lst ) {
    bool leaf = true ;
    for ( auto y : v[ x ] ) {
        if ( y == lst ) { continue ; }
        leaf = false ;
        dfs ( y , x ) ;
    }
    if ( leaf == true && cnt[ x ] > 0 ) {
        ord.push_back ( x ) ;
    }
}


vector < pair < int , int > > ans ;

void solve ( ) {
    cin >> n ;
    for ( int i = 1 , x , y ; i < n ; ++ i ) {
        cin >> x >> y ;
        v[ x ].push_back ( y ) ;
        v[ y ].push_back ( x ) ;
    }
    for ( int i = 1 ; i <= n ; ++ i ) {
        if ( ( int ) v[ i ].size ( ) >= 2 ) {
            root = i ; break ;
        }
    }
    init ( root ,  -1 ) ;
    root = get_centroid ( root , -1 , cnt[ root ] / 2 + 1 ) ;
    init ( root , -1 ) ;

    dfs ( root , -1 ) ;
    for ( int i = 0 ; i < cnt[ root ] / 2 ; ++ i ) {
        ans.push_back ( { ord[ i ] , ord[ i + cnt[ root ] / 2 ] } ) ;
    }
    if ( ( cnt[ root ] % 2 ) == 1 ) {
        ans.push_back ( { root , ord.back ( ) } ) ;
    }
    int sz = ans.size ( ) ;
    cout << sz << "\n" ;
    for ( auto [ x , y ] : ans ) {
        cout << x << " " << y << "\n" ;
    }
}

int main ( ) {
    ios_base :: sync_with_stdio ( false ) ;
    cin.tie ( NULL ) ;
    int t = 1 ; // cin >> t ; 
    while ( t -- ) { solve ( ) ; }
    return 0 ;
}

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 5 ms 12076 KB Output is correct
4 Correct 6 ms 12060 KB Output is correct
5 Correct 6 ms 12084 KB Output is correct
6 Correct 7 ms 11988 KB Output is correct
7 Correct 6 ms 12076 KB Output is correct
8 Correct 6 ms 12072 KB Output is correct
9 Correct 6 ms 12076 KB Output is correct
10 Correct 7 ms 11988 KB Output is correct
11 Correct 6 ms 12076 KB Output is correct
12 Correct 8 ms 11988 KB Output is correct
13 Correct 7 ms 11988 KB Output is correct
14 Correct 8 ms 11996 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 7 ms 11988 KB Output is correct
18 Correct 8 ms 11988 KB Output is correct
19 Correct 6 ms 11988 KB Output is correct
20 Correct 6 ms 11988 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 5 ms 12076 KB Output is correct
4 Correct 6 ms 12060 KB Output is correct
5 Correct 6 ms 12084 KB Output is correct
6 Correct 7 ms 11988 KB Output is correct
7 Correct 6 ms 12076 KB Output is correct
8 Correct 6 ms 12072 KB Output is correct
9 Correct 6 ms 12076 KB Output is correct
10 Correct 7 ms 11988 KB Output is correct
11 Correct 6 ms 12076 KB Output is correct
12 Correct 8 ms 11988 KB Output is correct
13 Correct 7 ms 11988 KB Output is correct
14 Correct 8 ms 11996 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 7 ms 11988 KB Output is correct
18 Correct 8 ms 11988 KB Output is correct
19 Correct 6 ms 11988 KB Output is correct
20 Correct 6 ms 11988 KB Output is correct
21 Correct 6 ms 11988 KB Output is correct
22 Correct 8 ms 12212 KB Output is correct
23 Correct 7 ms 12128 KB Output is correct
24 Correct 7 ms 12116 KB Output is correct
25 Correct 8 ms 12092 KB Output is correct
26 Correct 7 ms 12116 KB Output is correct
27 Correct 8 ms 12152 KB Output is correct
28 Correct 7 ms 12116 KB Output is correct
29 Correct 7 ms 12152 KB Output is correct
30 Correct 6 ms 11988 KB Output is correct
31 Correct 9 ms 12116 KB Output is correct
32 Correct 6 ms 11988 KB Output is correct
33 Correct 6 ms 12072 KB Output is correct
34 Correct 6 ms 11988 KB Output is correct
35 Correct 6 ms 11988 KB Output is correct
36 Correct 6 ms 11988 KB Output is correct
37 Correct 7 ms 12080 KB Output is correct
38 Correct 7 ms 12116 KB Output is correct
39 Correct 6 ms 12072 KB Output is correct
40 Correct 6 ms 12072 KB Output is correct
41 Correct 6 ms 11988 KB Output is correct
42 Correct 6 ms 12116 KB Output is correct
43 Correct 7 ms 12116 KB Output is correct
44 Correct 6 ms 11988 KB Output is correct
45 Correct 6 ms 11988 KB Output is correct
46 Correct 6 ms 12136 KB Output is correct
47 Correct 7 ms 11988 KB Output is correct
48 Correct 6 ms 11988 KB Output is correct
49 Correct 7 ms 12116 KB Output is correct
50 Correct 6 ms 11988 KB Output is correct
51 Correct 6 ms 12076 KB Output is correct
52 Correct 6 ms 11988 KB Output is correct
53 Correct 7 ms 12116 KB Output is correct
54 Correct 7 ms 12016 KB Output is correct
55 Correct 6 ms 12072 KB Output is correct
56 Correct 8 ms 12028 KB Output is correct
57 Correct 7 ms 12072 KB Output is correct
58 Correct 8 ms 12116 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 5 ms 12076 KB Output is correct
4 Correct 6 ms 12060 KB Output is correct
5 Correct 6 ms 12084 KB Output is correct
6 Correct 7 ms 11988 KB Output is correct
7 Correct 6 ms 12076 KB Output is correct
8 Correct 6 ms 12072 KB Output is correct
9 Correct 6 ms 12076 KB Output is correct
10 Correct 7 ms 11988 KB Output is correct
11 Correct 6 ms 12076 KB Output is correct
12 Correct 8 ms 11988 KB Output is correct
13 Correct 7 ms 11988 KB Output is correct
14 Correct 8 ms 11996 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 7 ms 11988 KB Output is correct
18 Correct 8 ms 11988 KB Output is correct
19 Correct 6 ms 11988 KB Output is correct
20 Correct 6 ms 11988 KB Output is correct
21 Correct 6 ms 11988 KB Output is correct
22 Correct 8 ms 12212 KB Output is correct
23 Correct 7 ms 12128 KB Output is correct
24 Correct 7 ms 12116 KB Output is correct
25 Correct 8 ms 12092 KB Output is correct
26 Correct 7 ms 12116 KB Output is correct
27 Correct 8 ms 12152 KB Output is correct
28 Correct 7 ms 12116 KB Output is correct
29 Correct 7 ms 12152 KB Output is correct
30 Correct 6 ms 11988 KB Output is correct
31 Correct 9 ms 12116 KB Output is correct
32 Correct 6 ms 11988 KB Output is correct
33 Correct 6 ms 12072 KB Output is correct
34 Correct 6 ms 11988 KB Output is correct
35 Correct 6 ms 11988 KB Output is correct
36 Correct 6 ms 11988 KB Output is correct
37 Correct 7 ms 12080 KB Output is correct
38 Correct 7 ms 12116 KB Output is correct
39 Correct 6 ms 12072 KB Output is correct
40 Correct 6 ms 12072 KB Output is correct
41 Correct 6 ms 11988 KB Output is correct
42 Correct 6 ms 12116 KB Output is correct
43 Correct 7 ms 12116 KB Output is correct
44 Correct 6 ms 11988 KB Output is correct
45 Correct 6 ms 11988 KB Output is correct
46 Correct 6 ms 12136 KB Output is correct
47 Correct 7 ms 11988 KB Output is correct
48 Correct 6 ms 11988 KB Output is correct
49 Correct 7 ms 12116 KB Output is correct
50 Correct 6 ms 11988 KB Output is correct
51 Correct 6 ms 12076 KB Output is correct
52 Correct 6 ms 11988 KB Output is correct
53 Correct 7 ms 12116 KB Output is correct
54 Correct 7 ms 12016 KB Output is correct
55 Correct 6 ms 12072 KB Output is correct
56 Correct 8 ms 12028 KB Output is correct
57 Correct 7 ms 12072 KB Output is correct
58 Correct 8 ms 12116 KB Output is correct
59 Correct 348 ms 40764 KB Output is correct
60 Correct 432 ms 44020 KB Output is correct
61 Correct 7 ms 11988 KB Output is correct
62 Correct 7 ms 12080 KB Output is correct
63 Correct 312 ms 37840 KB Output is correct
64 Correct 8 ms 12628 KB Output is correct
65 Correct 16 ms 14676 KB Output is correct
66 Correct 217 ms 34656 KB Output is correct
67 Correct 618 ms 59340 KB Output is correct
68 Correct 628 ms 60268 KB Output is correct
69 Correct 13 ms 13140 KB Output is correct
70 Correct 79 ms 23060 KB Output is correct
71 Correct 284 ms 47708 KB Output is correct
72 Correct 301 ms 46392 KB Output is correct
73 Correct 102 ms 20452 KB Output is correct
74 Correct 463 ms 42520 KB Output is correct
75 Correct 25 ms 15820 KB Output is correct
76 Correct 290 ms 47388 KB Output is correct
77 Correct 282 ms 47472 KB Output is correct
78 Correct 31 ms 16616 KB Output is correct
79 Correct 632 ms 56392 KB Output is correct
80 Correct 8 ms 12372 KB Output is correct
81 Correct 111 ms 23088 KB Output is correct
82 Correct 388 ms 44896 KB Output is correct
83 Correct 454 ms 42540 KB Output is correct
84 Correct 460 ms 42508 KB Output is correct
85 Correct 463 ms 42504 KB Output is correct
86 Correct 426 ms 43948 KB Output is correct
87 Correct 442 ms 44016 KB Output is correct