답안 #625291

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
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

#	결과	실행 시간	메모리	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

#	결과	실행 시간	메모리	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

#	결과	실행 시간	메모리	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

답안 #625291

Compilation message

Subtask #1 18.0 / 18.0

Subtask #2 45.0 / 45.0

Subtask #3 37.0 / 37.0

Subtask #1
18.0 / 18.0

Subtask #2
45.0 / 45.0

Subtask #3
37.0 / 37.0