Submission #394597

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
394597	2021-04-27T05:04:31 Z	AriaH	Network (BOI15_net)	C++11	100 / 100	589 ms	66548 KB

/** vaziat sorati ghermeze **/

#pragma GCC optimize("O2")
#include <bits/stdc++.h>
using namespace std;

typedef long long                   ll;
typedef long double                 ld;
typedef pair<int,int>               pii;
typedef pair<ll,ll>                 pll;
#define all(x)                      (x).begin(),(x).end()
#define F                           first
#define S                           second
#define Mp                          make_pair
#define SZ(x)			    		(int)x.size()
#define fast_io                     ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io                     freopen("in.txt" , "r+" , stdin) ; freopen("out.txt" , "w+" , stdout);

const int N = 1e6 + 10;
const ll mod = 1e9 + 7;
const ll mod2 = 998244353;
const ll inf = 8e18;
const int LOG = 22;

ll pw(ll a , ll b, ll M)  { return (!b ? 1 : (b & 1 ? (a * pw(a * a % M, b / 2, M)) % M : pw(a * a % M, b / 2, M))); }

int n, ptr, St[N];

vector < int > leaf, G[N];

void dfs(int v, int P = 0)
{
	St[v] = ++ ptr;
	for(auto u : G[v])
	{
		if(u == P) continue;
		dfs(u, v);
	}
}

bool cmp(int i, int j)
{
	return St[i] < St[j];
}

int main()
{
	scanf("%d", &n);
	for(int i = 1; i < n ;i ++)
	{
		int a, b;
		scanf("%d%d", &a, &b);
		G[a].push_back(b);
		G[b].push_back(a);
	}
	int root = 1;
	for(int i = 1; i <= n; i ++)
	{
		if(SZ(G[i]) > 1) root = i;
		if(SZ(G[i]) == 1) leaf.push_back(i);
	}
	dfs(root);
	/*for(int i = 1; i <= n; i ++)
	{
		printf("%d ", St[i]);
	}
	printf("\n");*/
	/*for(auto x : leaf)
	{
		printf("%d ", x);
	}
	printf("\n");*/
	sort(all(leaf), cmp);
	int cu = SZ(leaf) >> 1;
	printf("%d\n", SZ(leaf) - cu);
	for(int i = 0; i < SZ(leaf) - cu; i ++)
	{
		printf("%d %d\n", leaf[i], leaf[i + cu]);
	}
    return 0;
}

/** test corner cases(n = 1?) watch for overflow or minus indices **/

Compilation message

net.cpp: In function 'int main()':
net.cpp:48:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   48 |  scanf("%d", &n);
      |  ~~~~~^~~~~~~~~~
net.cpp:52:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   52 |   scanf("%d%d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	15 ms	23696 KB	Output is correct
2	Correct	16 ms	23744 KB	Output is correct
3	Correct	16 ms	23756 KB	Output is correct
4	Correct	16 ms	23756 KB	Output is correct
5	Correct	15 ms	23788 KB	Output is correct
6	Correct	17 ms	23792 KB	Output is correct
7	Correct	15 ms	23780 KB	Output is correct
8	Correct	17 ms	23756 KB	Output is correct
9	Correct	16 ms	23788 KB	Output is correct
10	Correct	18 ms	23792 KB	Output is correct
11	Correct	16 ms	23704 KB	Output is correct
12	Correct	16 ms	23696 KB	Output is correct
13	Correct	16 ms	23724 KB	Output is correct
14	Correct	16 ms	23756 KB	Output is correct
15	Correct	17 ms	23716 KB	Output is correct
16	Correct	16 ms	23756 KB	Output is correct
17	Correct	16 ms	23756 KB	Output is correct
18	Correct	15 ms	23756 KB	Output is correct
19	Correct	15 ms	23724 KB	Output is correct
20	Correct	16 ms	23724 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	15 ms	23696 KB	Output is correct
2	Correct	16 ms	23744 KB	Output is correct
3	Correct	16 ms	23756 KB	Output is correct
4	Correct	16 ms	23756 KB	Output is correct
5	Correct	15 ms	23788 KB	Output is correct
6	Correct	17 ms	23792 KB	Output is correct
7	Correct	15 ms	23780 KB	Output is correct
8	Correct	17 ms	23756 KB	Output is correct
9	Correct	16 ms	23788 KB	Output is correct
10	Correct	18 ms	23792 KB	Output is correct
11	Correct	16 ms	23704 KB	Output is correct
12	Correct	16 ms	23696 KB	Output is correct
13	Correct	16 ms	23724 KB	Output is correct
14	Correct	16 ms	23756 KB	Output is correct
15	Correct	17 ms	23716 KB	Output is correct
16	Correct	16 ms	23756 KB	Output is correct
17	Correct	16 ms	23756 KB	Output is correct
18	Correct	15 ms	23756 KB	Output is correct
19	Correct	15 ms	23724 KB	Output is correct
20	Correct	16 ms	23724 KB	Output is correct
21	Correct	16 ms	23756 KB	Output is correct
22	Correct	17 ms	23856 KB	Output is correct
23	Correct	16 ms	23800 KB	Output is correct
24	Correct	16 ms	23796 KB	Output is correct
25	Correct	16 ms	23864 KB	Output is correct
26	Correct	16 ms	23756 KB	Output is correct
27	Correct	16 ms	23884 KB	Output is correct
28	Correct	18 ms	23884 KB	Output is correct
29	Correct	16 ms	23756 KB	Output is correct
30	Correct	16 ms	23756 KB	Output is correct
31	Correct	17 ms	23884 KB	Output is correct
32	Correct	16 ms	23832 KB	Output is correct
33	Correct	16 ms	23716 KB	Output is correct
34	Correct	15 ms	23732 KB	Output is correct
35	Correct	15 ms	23760 KB	Output is correct
36	Correct	15 ms	23768 KB	Output is correct
37	Correct	19 ms	23828 KB	Output is correct
38	Correct	16 ms	23816 KB	Output is correct
39	Correct	15 ms	23784 KB	Output is correct
40	Correct	15 ms	23756 KB	Output is correct
41	Correct	17 ms	23760 KB	Output is correct
42	Correct	16 ms	23756 KB	Output is correct
43	Correct	16 ms	23772 KB	Output is correct
44	Correct	16 ms	23756 KB	Output is correct
45	Correct	16 ms	23772 KB	Output is correct
46	Correct	16 ms	23820 KB	Output is correct
47	Correct	16 ms	23728 KB	Output is correct
48	Correct	15 ms	23768 KB	Output is correct
49	Correct	17 ms	23756 KB	Output is correct
50	Correct	16 ms	23788 KB	Output is correct
51	Correct	16 ms	23760 KB	Output is correct
52	Correct	15 ms	23736 KB	Output is correct
53	Correct	16 ms	23756 KB	Output is correct
54	Correct	15 ms	23732 KB	Output is correct
55	Correct	15 ms	23808 KB	Output is correct
56	Correct	15 ms	23756 KB	Output is correct
57	Correct	15 ms	23716 KB	Output is correct
58	Correct	18 ms	23840 KB	Output is correct

Subtask #3
37.0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	15 ms	23696 KB	Output is correct
2	Correct	16 ms	23744 KB	Output is correct
3	Correct	16 ms	23756 KB	Output is correct
4	Correct	16 ms	23756 KB	Output is correct
5	Correct	15 ms	23788 KB	Output is correct
6	Correct	17 ms	23792 KB	Output is correct
7	Correct	15 ms	23780 KB	Output is correct
8	Correct	17 ms	23756 KB	Output is correct
9	Correct	16 ms	23788 KB	Output is correct
10	Correct	18 ms	23792 KB	Output is correct
11	Correct	16 ms	23704 KB	Output is correct
12	Correct	16 ms	23696 KB	Output is correct
13	Correct	16 ms	23724 KB	Output is correct
14	Correct	16 ms	23756 KB	Output is correct
15	Correct	17 ms	23716 KB	Output is correct
16	Correct	16 ms	23756 KB	Output is correct
17	Correct	16 ms	23756 KB	Output is correct
18	Correct	15 ms	23756 KB	Output is correct
19	Correct	15 ms	23724 KB	Output is correct
20	Correct	16 ms	23724 KB	Output is correct
21	Correct	16 ms	23756 KB	Output is correct
22	Correct	17 ms	23856 KB	Output is correct
23	Correct	16 ms	23800 KB	Output is correct
24	Correct	16 ms	23796 KB	Output is correct
25	Correct	16 ms	23864 KB	Output is correct
26	Correct	16 ms	23756 KB	Output is correct
27	Correct	16 ms	23884 KB	Output is correct
28	Correct	18 ms	23884 KB	Output is correct
29	Correct	16 ms	23756 KB	Output is correct
30	Correct	16 ms	23756 KB	Output is correct
31	Correct	17 ms	23884 KB	Output is correct
32	Correct	16 ms	23832 KB	Output is correct
33	Correct	16 ms	23716 KB	Output is correct
34	Correct	15 ms	23732 KB	Output is correct
35	Correct	15 ms	23760 KB	Output is correct
36	Correct	15 ms	23768 KB	Output is correct
37	Correct	19 ms	23828 KB	Output is correct
38	Correct	16 ms	23816 KB	Output is correct
39	Correct	15 ms	23784 KB	Output is correct
40	Correct	15 ms	23756 KB	Output is correct
41	Correct	17 ms	23760 KB	Output is correct
42	Correct	16 ms	23756 KB	Output is correct
43	Correct	16 ms	23772 KB	Output is correct
44	Correct	16 ms	23756 KB	Output is correct
45	Correct	16 ms	23772 KB	Output is correct
46	Correct	16 ms	23820 KB	Output is correct
47	Correct	16 ms	23728 KB	Output is correct
48	Correct	15 ms	23768 KB	Output is correct
49	Correct	17 ms	23756 KB	Output is correct
50	Correct	16 ms	23788 KB	Output is correct
51	Correct	16 ms	23760 KB	Output is correct
52	Correct	15 ms	23736 KB	Output is correct
53	Correct	16 ms	23756 KB	Output is correct
54	Correct	15 ms	23732 KB	Output is correct
55	Correct	15 ms	23808 KB	Output is correct
56	Correct	15 ms	23756 KB	Output is correct
57	Correct	15 ms	23716 KB	Output is correct
58	Correct	18 ms	23840 KB	Output is correct
59	Correct	457 ms	45212 KB	Output is correct
60	Correct	545 ms	47604 KB	Output is correct
61	Correct	15 ms	23756 KB	Output is correct
62	Correct	15 ms	23792 KB	Output is correct
63	Correct	397 ms	43324 KB	Output is correct
64	Correct	17 ms	24140 KB	Output is correct
65	Correct	27 ms	25548 KB	Output is correct
66	Correct	191 ms	36928 KB	Output is correct
67	Correct	547 ms	66548 KB	Output is correct
68	Correct	541 ms	59348 KB	Output is correct
69	Correct	25 ms	24652 KB	Output is correct
70	Correct	129 ms	33228 KB	Output is correct
71	Correct	434 ms	50508 KB	Output is correct
72	Correct	462 ms	49940 KB	Output is correct
73	Correct	109 ms	31276 KB	Output is correct
74	Correct	589 ms	46564 KB	Output is correct
75	Correct	49 ms	27204 KB	Output is correct
76	Correct	434 ms	50192 KB	Output is correct
77	Correct	433 ms	50652 KB	Output is correct
78	Correct	47 ms	27300 KB	Output is correct
79	Correct	522 ms	53768 KB	Output is correct
80	Correct	18 ms	24012 KB	Output is correct
81	Correct	143 ms	33268 KB	Output is correct
82	Correct	509 ms	48584 KB	Output is correct
83	Correct	559 ms	46476 KB	Output is correct
84	Correct	545 ms	46592 KB	Output is correct
85	Correct	552 ms	46500 KB	Output is correct
86	Correct	552 ms	47508 KB	Output is correct
87	Correct	577 ms	47532 KB	Output is correct

Submission #394597

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