Submission #166592

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
166592	2019-12-03T00:37:04 Z	Lawliet	Network (BOI15_net)	C++17	100 / 100	879 ms	94788 KB

#include <bits/stdc++.h>

using namespace std;
typedef pair<int,int> pii;

const int MAXN = 500010;

int n;

int sub[MAXN];

vector< int > adj[MAXN];
vector< int > group[MAXN];

set< pii > s;

void DFS(int cur, int p, int t)
{
	if( adj[cur].size() == 1 )
	{
		sub[ cur ] = 1;

		group[ t ].push_back( cur );

		return;
	}

	for(int i = 0 ; i < adj[cur].size() ; i++)
	{
		int viz = adj[cur][i];

		if( viz == p ) continue;

		DFS( viz , cur , t );

		sub[ cur ] += sub[ viz ];
	}
}

int findPendantCentroid(int cur, int p, int s)
{
	for(int i = 0 ; i < adj[cur].size() ; i++)
	{
		int viz = adj[cur][i];

		if( viz == p ) continue;

		if( 2*sub[viz] > s ) return findPendantCentroid( viz , cur , s );
	}

	return cur;
}

void add(int i) { s.insert( { -group[i].size() , i } ); }

int main()
{
	scanf("%d",&n);

	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 );
	}

	int root = 0;

	for(int i = 1 ; i <= n ; i++)
		if( adj[i].size() > 1 ) root = i;

	DFS( root , root , 0 );

	int t = 0;
	int qtdLeafs = sub[root];
	int c = findPendantCentroid( root , root , sub[root] );

	for(int i = 0 ; i < adj[c].size() ; i++)
	{
		int viz = adj[c][i];

		DFS( viz , c , ++t );

		add( t );
	}

	int lastLeaf;

	printf("%d\n",( qtdLeafs + 1 )/2);

	while( qtdLeafs > 1 )
	{
		int curU = s.begin()->second; s.erase( s.begin() );
		int curV = s.begin()->second; s.erase( s.begin() );

		printf("%d %d\n",group[curU].back(),group[curV].back());

		lastLeaf = group[curU].back();

		qtdLeafs -= 2;

		group[ curU ].pop_back();
		group[ curV ].pop_back();

		if( !group[ curU ].empty() ) add( curU );
		if( !group[ curV ].empty() ) add( curV );
	}

	if( qtdLeafs == 1 )
	{
		int curU = s.begin()->second; s.erase( s.begin() );

		printf("%d %d\n",lastLeaf,group[curU].back());
	}
}

Compilation message

net.cpp: In function 'void DFS(int, int, int)':
net.cpp:28:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0 ; i < adj[cur].size() ; i++)
                  ~~^~~~~~~~~~~~~~~~~
net.cpp: In function 'int findPendantCentroid(int, int, int)':
net.cpp:42:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0 ; i < adj[cur].size() ; i++)
                  ~~^~~~~~~~~~~~~~~~~
net.cpp: In function 'int main()':
net.cpp:80:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0 ; i < adj[c].size() ; i++)
                  ~~^~~~~~~~~~~~~~~
net.cpp:58:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
net.cpp:63:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&U,&V);
   ~~~~~^~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	27 ms	23800 KB	Output is correct
2	Correct	25 ms	23800 KB	Output is correct
3	Correct	25 ms	23800 KB	Output is correct
4	Correct	24 ms	23800 KB	Output is correct
5	Correct	24 ms	23800 KB	Output is correct
6	Correct	25 ms	23800 KB	Output is correct
7	Correct	24 ms	23800 KB	Output is correct
8	Correct	24 ms	23800 KB	Output is correct
9	Correct	26 ms	23900 KB	Output is correct
10	Correct	24 ms	23800 KB	Output is correct
11	Correct	25 ms	23800 KB	Output is correct
12	Correct	25 ms	23800 KB	Output is correct
13	Correct	25 ms	23800 KB	Output is correct
14	Correct	25 ms	23800 KB	Output is correct
15	Correct	25 ms	23800 KB	Output is correct
16	Correct	25 ms	23800 KB	Output is correct
17	Correct	25 ms	23800 KB	Output is correct
18	Correct	24 ms	23800 KB	Output is correct
19	Correct	28 ms	23800 KB	Output is correct
20	Correct	24 ms	23800 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	27 ms	23800 KB	Output is correct
2	Correct	25 ms	23800 KB	Output is correct
3	Correct	25 ms	23800 KB	Output is correct
4	Correct	24 ms	23800 KB	Output is correct
5	Correct	24 ms	23800 KB	Output is correct
6	Correct	25 ms	23800 KB	Output is correct
7	Correct	24 ms	23800 KB	Output is correct
8	Correct	24 ms	23800 KB	Output is correct
9	Correct	26 ms	23900 KB	Output is correct
10	Correct	24 ms	23800 KB	Output is correct
11	Correct	25 ms	23800 KB	Output is correct
12	Correct	25 ms	23800 KB	Output is correct
13	Correct	25 ms	23800 KB	Output is correct
14	Correct	25 ms	23800 KB	Output is correct
15	Correct	25 ms	23800 KB	Output is correct
16	Correct	25 ms	23800 KB	Output is correct
17	Correct	25 ms	23800 KB	Output is correct
18	Correct	24 ms	23800 KB	Output is correct
19	Correct	28 ms	23800 KB	Output is correct
20	Correct	24 ms	23800 KB	Output is correct
21	Correct	24 ms	23800 KB	Output is correct
22	Correct	27 ms	24056 KB	Output is correct
23	Correct	39 ms	24056 KB	Output is correct
24	Correct	26 ms	24056 KB	Output is correct
25	Correct	26 ms	24056 KB	Output is correct
26	Correct	26 ms	23960 KB	Output is correct
27	Correct	25 ms	23928 KB	Output is correct
28	Correct	26 ms	23928 KB	Output is correct
29	Correct	27 ms	23928 KB	Output is correct
30	Correct	26 ms	23800 KB	Output is correct
31	Correct	26 ms	23928 KB	Output is correct
32	Correct	28 ms	23800 KB	Output is correct
33	Correct	24 ms	23800 KB	Output is correct
34	Correct	24 ms	23800 KB	Output is correct
35	Correct	24 ms	23800 KB	Output is correct
36	Correct	25 ms	23800 KB	Output is correct
37	Correct	25 ms	23800 KB	Output is correct
38	Correct	25 ms	23900 KB	Output is correct
39	Correct	25 ms	23800 KB	Output is correct
40	Correct	24 ms	23800 KB	Output is correct
41	Correct	25 ms	23800 KB	Output is correct
42	Correct	25 ms	23928 KB	Output is correct
43	Correct	25 ms	23928 KB	Output is correct
44	Correct	50 ms	23748 KB	Output is correct
45	Correct	25 ms	23800 KB	Output is correct
46	Correct	25 ms	23928 KB	Output is correct
47	Correct	25 ms	23800 KB	Output is correct
48	Correct	25 ms	23800 KB	Output is correct
49	Correct	50 ms	23928 KB	Output is correct
50	Correct	26 ms	23800 KB	Output is correct
51	Correct	24 ms	23800 KB	Output is correct
52	Correct	25 ms	23800 KB	Output is correct
53	Correct	25 ms	23800 KB	Output is correct
54	Correct	42 ms	23928 KB	Output is correct
55	Correct	25 ms	23784 KB	Output is correct
56	Correct	24 ms	23800 KB	Output is correct
57	Correct	24 ms	23928 KB	Output is correct
58	Correct	26 ms	23928 KB	Output is correct

Subtask #3
37.0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	27 ms	23800 KB	Output is correct
2	Correct	25 ms	23800 KB	Output is correct
3	Correct	25 ms	23800 KB	Output is correct
4	Correct	24 ms	23800 KB	Output is correct
5	Correct	24 ms	23800 KB	Output is correct
6	Correct	25 ms	23800 KB	Output is correct
7	Correct	24 ms	23800 KB	Output is correct
8	Correct	24 ms	23800 KB	Output is correct
9	Correct	26 ms	23900 KB	Output is correct
10	Correct	24 ms	23800 KB	Output is correct
11	Correct	25 ms	23800 KB	Output is correct
12	Correct	25 ms	23800 KB	Output is correct
13	Correct	25 ms	23800 KB	Output is correct
14	Correct	25 ms	23800 KB	Output is correct
15	Correct	25 ms	23800 KB	Output is correct
16	Correct	25 ms	23800 KB	Output is correct
17	Correct	25 ms	23800 KB	Output is correct
18	Correct	24 ms	23800 KB	Output is correct
19	Correct	28 ms	23800 KB	Output is correct
20	Correct	24 ms	23800 KB	Output is correct
21	Correct	24 ms	23800 KB	Output is correct
22	Correct	27 ms	24056 KB	Output is correct
23	Correct	39 ms	24056 KB	Output is correct
24	Correct	26 ms	24056 KB	Output is correct
25	Correct	26 ms	24056 KB	Output is correct
26	Correct	26 ms	23960 KB	Output is correct
27	Correct	25 ms	23928 KB	Output is correct
28	Correct	26 ms	23928 KB	Output is correct
29	Correct	27 ms	23928 KB	Output is correct
30	Correct	26 ms	23800 KB	Output is correct
31	Correct	26 ms	23928 KB	Output is correct
32	Correct	28 ms	23800 KB	Output is correct
33	Correct	24 ms	23800 KB	Output is correct
34	Correct	24 ms	23800 KB	Output is correct
35	Correct	24 ms	23800 KB	Output is correct
36	Correct	25 ms	23800 KB	Output is correct
37	Correct	25 ms	23800 KB	Output is correct
38	Correct	25 ms	23900 KB	Output is correct
39	Correct	25 ms	23800 KB	Output is correct
40	Correct	24 ms	23800 KB	Output is correct
41	Correct	25 ms	23800 KB	Output is correct
42	Correct	25 ms	23928 KB	Output is correct
43	Correct	25 ms	23928 KB	Output is correct
44	Correct	50 ms	23748 KB	Output is correct
45	Correct	25 ms	23800 KB	Output is correct
46	Correct	25 ms	23928 KB	Output is correct
47	Correct	25 ms	23800 KB	Output is correct
48	Correct	25 ms	23800 KB	Output is correct
49	Correct	50 ms	23928 KB	Output is correct
50	Correct	26 ms	23800 KB	Output is correct
51	Correct	24 ms	23800 KB	Output is correct
52	Correct	25 ms	23800 KB	Output is correct
53	Correct	25 ms	23800 KB	Output is correct
54	Correct	42 ms	23928 KB	Output is correct
55	Correct	25 ms	23784 KB	Output is correct
56	Correct	24 ms	23800 KB	Output is correct
57	Correct	24 ms	23928 KB	Output is correct
58	Correct	26 ms	23928 KB	Output is correct
59	Correct	687 ms	61304 KB	Output is correct
60	Correct	692 ms	54016 KB	Output is correct
61	Correct	24 ms	23932 KB	Output is correct
62	Correct	24 ms	23800 KB	Output is correct
63	Correct	597 ms	54640 KB	Output is correct
64	Correct	28 ms	24312 KB	Output is correct
65	Correct	41 ms	25852 KB	Output is correct
66	Correct	263 ms	39416 KB	Output is correct
67	Correct	866 ms	79360 KB	Output is correct
68	Correct	879 ms	69828 KB	Output is correct
69	Correct	39 ms	25848 KB	Output is correct
70	Correct	201 ms	44568 KB	Output is correct
71	Correct	745 ms	94788 KB	Output is correct
72	Correct	690 ms	89344 KB	Output is correct
73	Correct	165 ms	31728 KB	Output is correct
74	Correct	684 ms	53028 KB	Output is correct
75	Correct	67 ms	29304 KB	Output is correct
76	Correct	585 ms	74960 KB	Output is correct
77	Correct	603 ms	75980 KB	Output is correct
78	Correct	67 ms	27768 KB	Output is correct
79	Correct	835 ms	62396 KB	Output is correct
80	Correct	29 ms	24184 KB	Output is correct
81	Correct	214 ms	40380 KB	Output is correct
82	Correct	726 ms	73352 KB	Output is correct
83	Correct	735 ms	52840 KB	Output is correct
84	Correct	729 ms	53032 KB	Output is correct
85	Correct	681 ms	52972 KB	Output is correct
86	Correct	669 ms	54564 KB	Output is correct
87	Correct	668 ms	54780 KB	Output is correct

Submission #166592

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