답안 #476661

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
476661	2021-09-28T03:09:36 Z	thiago_bastos	Network (BOI15_net)	C++17	100 / 100	596 ms	92572 KB

#include "bits/stdc++.h"
 
using namespace std;

using i64 = long long;
using u64 = unsigned long long;
using i32 = int;
using u32 = unsigned;
using i16 = short;
using u16 = unsigned short;
using ld = long double;
using ii = pair<int, int>;

vector<vector<int>> g;
vector<int> leaves;
int n;

void preprocess(int u, int p = -1) {
	leaves[u] = 0;
	if((int)g[u].size() == 1) ++leaves[u];
	for(int v : g[u]) {
		if(v == p) continue;
		preprocess(v, u);
		leaves[u] += leaves[v];
	}
}

int dfs(int u, int p = -1) {
	
	int max_leaves = 0;
	
	if(p != -1) max_leaves = leaves[0] - leaves[u];
	
	for(int v : g[u]) {
		if(v == p) continue;
		max_leaves = max(max_leaves, leaves[v]);
	}
	
	if(max_leaves <= leaves[0] / 2) return u;
	
	for(int v : g[u]) {
		if(v == p) continue;
		int w = dfs(v, u);
		if(w != -1) return w;
	}
	
	return -1;
}

void solve() {
	cin >> n;
	
	g.resize(n);
	leaves.resize(n);
	
	for(int i = 1; i < n; ++i) {
		int u, v;
		cin >> u >> v;
		--u, --v;
		g[u].push_back(v);
		g[v].push_back(u);
	}
	
	preprocess(0);
	
	int v = dfs(0);

	vector<vector<int>> F;
	
	function<void(int, int)> get = [&](int u, int p) {
		if(g[u].size() == 1) F.back().push_back(u);
		for(int v : g[u]) {
			if(v == p) continue;
			get(v, u);
		}
	};
		
	for(int u : g[v]) {
		F.push_back({});
		get(u, v);
	}
	
	vector<ii> pairs;
	set<ii> S;
	
	for(int i = 0; i < (int)F.size(); ++i) S.insert({(int)F[i].size(), i});
	
	while(!S.empty()) {
		ii e = *S.begin();
		ii d = *S.rbegin();
		if(e == d) break;
		S.erase(S.begin());
		S.erase(d);
		pairs.emplace_back(F[e.second].back() + 1, F[d.second].back() + 1);
		F[e.second].pop_back();
		F[d.second].pop_back();
		if(--e.first) S.insert(e);
		if(--d.first) S.insert(d);
	}
	
	for(auto& x : F) {
		if(x.empty()) continue;
		int u = x.back();
		for(int v = 0; v < n; ++v) {
			if(v == u || g[v].size() > 1) continue;
			pairs.emplace_back(u + 1, v + 1);
			break;
		}
		break;
	}
	
	cout << pairs.size() << '\n';
	for(auto [u, v] : pairs) cout << u << ' ' << v << '\n';
}

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

Subtask #1
18.0 / 18.0

#	결과	실행 시간	메모리	Grader output
1	Correct	0 ms	204 KB	Output is correct
2	Correct	1 ms	204 KB	Output is correct
3	Correct	0 ms	204 KB	Output is correct
4	Correct	0 ms	204 KB	Output is correct
5	Correct	0 ms	204 KB	Output is correct
6	Correct	1 ms	204 KB	Output is correct
7	Correct	0 ms	312 KB	Output is correct
8	Correct	1 ms	204 KB	Output is correct
9	Correct	0 ms	204 KB	Output is correct
10	Correct	0 ms	204 KB	Output is correct
11	Correct	0 ms	204 KB	Output is correct
12	Correct	1 ms	204 KB	Output is correct
13	Correct	0 ms	204 KB	Output is correct
14	Correct	0 ms	204 KB	Output is correct
15	Correct	1 ms	204 KB	Output is correct
16	Correct	0 ms	204 KB	Output is correct
17	Correct	1 ms	204 KB	Output is correct
18	Correct	0 ms	204 KB	Output is correct
19	Correct	1 ms	204 KB	Output is correct
20	Correct	0 ms	204 KB	Output is correct

Subtask #2
45.0 / 45.0

#	결과	실행 시간	메모리	Grader output
1	Correct	0 ms	204 KB	Output is correct
2	Correct	1 ms	204 KB	Output is correct
3	Correct	0 ms	204 KB	Output is correct
4	Correct	0 ms	204 KB	Output is correct
5	Correct	0 ms	204 KB	Output is correct
6	Correct	1 ms	204 KB	Output is correct
7	Correct	0 ms	312 KB	Output is correct
8	Correct	1 ms	204 KB	Output is correct
9	Correct	0 ms	204 KB	Output is correct
10	Correct	0 ms	204 KB	Output is correct
11	Correct	0 ms	204 KB	Output is correct
12	Correct	1 ms	204 KB	Output is correct
13	Correct	0 ms	204 KB	Output is correct
14	Correct	0 ms	204 KB	Output is correct
15	Correct	1 ms	204 KB	Output is correct
16	Correct	0 ms	204 KB	Output is correct
17	Correct	1 ms	204 KB	Output is correct
18	Correct	0 ms	204 KB	Output is correct
19	Correct	1 ms	204 KB	Output is correct
20	Correct	0 ms	204 KB	Output is correct
21	Correct	1 ms	204 KB	Output is correct
22	Correct	1 ms	460 KB	Output is correct
23	Correct	1 ms	580 KB	Output is correct
24	Correct	2 ms	588 KB	Output is correct
25	Correct	1 ms	460 KB	Output is correct
26	Correct	1 ms	460 KB	Output is correct
27	Correct	1 ms	460 KB	Output is correct
28	Correct	1 ms	448 KB	Output is correct
29	Correct	1 ms	332 KB	Output is correct
30	Correct	0 ms	204 KB	Output is correct
31	Correct	1 ms	460 KB	Output is correct
32	Correct	0 ms	204 KB	Output is correct
33	Correct	1 ms	204 KB	Output is correct
34	Correct	1 ms	204 KB	Output is correct
35	Correct	1 ms	204 KB	Output is correct
36	Correct	0 ms	204 KB	Output is correct
37	Correct	1 ms	380 KB	Output is correct
38	Correct	1 ms	332 KB	Output is correct
39	Correct	1 ms	204 KB	Output is correct
40	Correct	0 ms	204 KB	Output is correct
41	Correct	0 ms	332 KB	Output is correct
42	Correct	1 ms	332 KB	Output is correct
43	Correct	1 ms	460 KB	Output is correct
44	Correct	1 ms	204 KB	Output is correct
45	Correct	1 ms	332 KB	Output is correct
46	Correct	1 ms	332 KB	Output is correct
47	Correct	1 ms	204 KB	Output is correct
48	Correct	1 ms	332 KB	Output is correct
49	Correct	1 ms	332 KB	Output is correct
50	Correct	1 ms	204 KB	Output is correct
51	Correct	0 ms	204 KB	Output is correct
52	Correct	1 ms	332 KB	Output is correct
53	Correct	1 ms	332 KB	Output is correct
54	Correct	0 ms	204 KB	Output is correct
55	Correct	1 ms	332 KB	Output is correct
56	Correct	1 ms	204 KB	Output is correct
57	Correct	1 ms	332 KB	Output is correct
58	Correct	1 ms	460 KB	Output is correct

Subtask #3
37.0 / 37.0

#	결과	실행 시간	메모리	Grader output
1	Correct	0 ms	204 KB	Output is correct
2	Correct	1 ms	204 KB	Output is correct
3	Correct	0 ms	204 KB	Output is correct
4	Correct	0 ms	204 KB	Output is correct
5	Correct	0 ms	204 KB	Output is correct
6	Correct	1 ms	204 KB	Output is correct
7	Correct	0 ms	312 KB	Output is correct
8	Correct	1 ms	204 KB	Output is correct
9	Correct	0 ms	204 KB	Output is correct
10	Correct	0 ms	204 KB	Output is correct
11	Correct	0 ms	204 KB	Output is correct
12	Correct	1 ms	204 KB	Output is correct
13	Correct	0 ms	204 KB	Output is correct
14	Correct	0 ms	204 KB	Output is correct
15	Correct	1 ms	204 KB	Output is correct
16	Correct	0 ms	204 KB	Output is correct
17	Correct	1 ms	204 KB	Output is correct
18	Correct	0 ms	204 KB	Output is correct
19	Correct	1 ms	204 KB	Output is correct
20	Correct	0 ms	204 KB	Output is correct
21	Correct	1 ms	204 KB	Output is correct
22	Correct	1 ms	460 KB	Output is correct
23	Correct	1 ms	580 KB	Output is correct
24	Correct	2 ms	588 KB	Output is correct
25	Correct	1 ms	460 KB	Output is correct
26	Correct	1 ms	460 KB	Output is correct
27	Correct	1 ms	460 KB	Output is correct
28	Correct	1 ms	448 KB	Output is correct
29	Correct	1 ms	332 KB	Output is correct
30	Correct	0 ms	204 KB	Output is correct
31	Correct	1 ms	460 KB	Output is correct
32	Correct	0 ms	204 KB	Output is correct
33	Correct	1 ms	204 KB	Output is correct
34	Correct	1 ms	204 KB	Output is correct
35	Correct	1 ms	204 KB	Output is correct
36	Correct	0 ms	204 KB	Output is correct
37	Correct	1 ms	380 KB	Output is correct
38	Correct	1 ms	332 KB	Output is correct
39	Correct	1 ms	204 KB	Output is correct
40	Correct	0 ms	204 KB	Output is correct
41	Correct	0 ms	332 KB	Output is correct
42	Correct	1 ms	332 KB	Output is correct
43	Correct	1 ms	460 KB	Output is correct
44	Correct	1 ms	204 KB	Output is correct
45	Correct	1 ms	332 KB	Output is correct
46	Correct	1 ms	332 KB	Output is correct
47	Correct	1 ms	204 KB	Output is correct
48	Correct	1 ms	332 KB	Output is correct
49	Correct	1 ms	332 KB	Output is correct
50	Correct	1 ms	204 KB	Output is correct
51	Correct	0 ms	204 KB	Output is correct
52	Correct	1 ms	332 KB	Output is correct
53	Correct	1 ms	332 KB	Output is correct
54	Correct	0 ms	204 KB	Output is correct
55	Correct	1 ms	332 KB	Output is correct
56	Correct	1 ms	204 KB	Output is correct
57	Correct	1 ms	332 KB	Output is correct
58	Correct	1 ms	460 KB	Output is correct
59	Correct	470 ms	50652 KB	Output is correct
60	Correct	474 ms	42716 KB	Output is correct
61	Correct	0 ms	204 KB	Output is correct
62	Correct	0 ms	204 KB	Output is correct
63	Correct	427 ms	43796 KB	Output is correct
64	Correct	2 ms	844 KB	Output is correct
65	Correct	13 ms	3148 KB	Output is correct
66	Correct	193 ms	23752 KB	Output is correct
67	Correct	545 ms	57160 KB	Output is correct
68	Correct	596 ms	55236 KB	Output is correct
69	Correct	11 ms	2952 KB	Output is correct
70	Correct	128 ms	27692 KB	Output is correct
71	Correct	510 ms	92572 KB	Output is correct
72	Correct	470 ms	86428 KB	Output is correct
73	Correct	101 ms	11452 KB	Output is correct
74	Correct	519 ms	40616 KB	Output is correct
75	Correct	35 ms	7804 KB	Output is correct
76	Correct	437 ms	70772 KB	Output is correct
77	Correct	496 ms	67940 KB	Output is correct
78	Correct	30 ms	5528 KB	Output is correct
79	Correct	573 ms	50644 KB	Output is correct
80	Correct	3 ms	764 KB	Output is correct
81	Correct	141 ms	22200 KB	Output is correct
82	Correct	581 ms	65736 KB	Output is correct
83	Correct	486 ms	40656 KB	Output is correct
84	Correct	507 ms	41240 KB	Output is correct
85	Correct	521 ms	41232 KB	Output is correct
86	Correct	474 ms	42952 KB	Output is correct
87	Correct	487 ms	43044 KB	Output is correct

답안 #476661

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