oj.uz

Submission #656028

# Submission time Handle Problem Language Result Execution time Memory
656028 2022-11-06T08:51:40 Z mosaev Network (BOI15_net) C++17
18 / 100
 23 ms 35796 KB 
#include <bits/stdc++.h>
#include <set>
#include <map>
#include <unordered_map>
using namespace std;
#define ll long long
#define N (ll)(5e5+5)
#define NP (2097155ll)
#define M ((ll)1e9+7)
#define fi first
#define se second
ll n, ct, r;
vector<ll> v[N];
vector<pair<ll, ll>> ans;
set<pair<ll, ll>> st[N], tmp;
void dfs(ll s, ll p) {
	ct++; if (v[s].size() == 1) { st[s].insert({ ct, s }); return; }
	for (auto x : v[s]) if (x != p) {
		dfs(x, s); if (st[x].size() > st[s].size()) swap(st[x], st[s]);
		for (auto y : st[x]) st[s].insert(y); st[x].clear();
	}
	tmp.clear(); for (auto x : st[s]) tmp.insert({ -x.first, x.second });
	while (st[s].size() > 2) {
		ans.push_back({ (*st[s].begin()).second, (*tmp.begin()).second });
		st[s].erase({ -(*tmp.begin()).first, tmp.begin()->second }); tmp.erase(tmp.begin());
		tmp.erase({ -st[s].begin()->first, st[s].begin()->second }); st[s].erase(st[s].begin());
	}
}
int main() {
#define int ll
	ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	cin >> n; ll a, b; for (int i = 1; i < n; i++) cin >> a >> b, v[a].push_back(b), v[b].push_back(a);
	for (int i = 1; i <= n; i++) if (v[i].size() > 1) r = i;
	dfs(r, 0);
	if (st[r].size() == 2) {
		pair<ll, ll> c = *st[r].begin(); st[r].erase(st[r].begin());
		ans.push_back({ c.second, st[r].begin()->second });
	}
	else if (st[r].size() == 1) {
		if (v[st[r].begin()->second][0] != r) ans.push_back({ r, st[r].begin()->second });
		else ans.push_back({ st[r].begin()->second, ans.back().second });
	}
	cout << ans.size() << '\n';
	for (auto x : ans) cout << x.first << ' ' << x.second << '\n';
}

Compilation message

net.cpp: In function 'void dfs(long long int, long long int)':
net.cpp:20:3: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   20 |   for (auto y : st[x]) st[s].insert(y); st[x].clear();
      |   ^~~
net.cpp:20:41: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   20 |   for (auto y : st[x]) st[s].insert(y); st[x].clear();
      |                                         ^~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 35484 KB Output is correct
2 Correct 21 ms 35540 KB Output is correct
3 Correct 19 ms 35544 KB Output is correct
4 Correct 19 ms 35540 KB Output is correct
5 Correct 19 ms 35524 KB Output is correct
6 Correct 18 ms 35528 KB Output is correct
7 Correct 18 ms 35540 KB Output is correct
8 Correct 20 ms 35408 KB Output is correct
9 Correct 18 ms 35548 KB Output is correct
10 Correct 18 ms 35540 KB Output is correct
11 Correct 18 ms 35552 KB Output is correct
12 Correct 18 ms 35540 KB Output is correct
13 Correct 17 ms 35548 KB Output is correct
14 Correct 19 ms 35508 KB Output is correct
15 Correct 20 ms 35452 KB Output is correct
16 Correct 19 ms 35540 KB Output is correct
17 Correct 18 ms 35552 KB Output is correct
18 Correct 18 ms 35452 KB Output is correct
19 Correct 17 ms 35496 KB Output is correct
20 Correct 20 ms 35544 KB Output is correct

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 35484 KB Output is correct
2 Correct 21 ms 35540 KB Output is correct
3 Correct 19 ms 35544 KB Output is correct
4 Correct 19 ms 35540 KB Output is correct
5 Correct 19 ms 35524 KB Output is correct
6 Correct 18 ms 35528 KB Output is correct
7 Correct 18 ms 35540 KB Output is correct
8 Correct 20 ms 35408 KB Output is correct
9 Correct 18 ms 35548 KB Output is correct
10 Correct 18 ms 35540 KB Output is correct
11 Correct 18 ms 35552 KB Output is correct
12 Correct 18 ms 35540 KB Output is correct
13 Correct 17 ms 35548 KB Output is correct
14 Correct 19 ms 35508 KB Output is correct
15 Correct 20 ms 35452 KB Output is correct
16 Correct 19 ms 35540 KB Output is correct
17 Correct 18 ms 35552 KB Output is correct
18 Correct 18 ms 35452 KB Output is correct
19 Correct 17 ms 35496 KB Output is correct
20 Correct 20 ms 35544 KB Output is correct
21 Correct 16 ms 35540 KB Output is correct
22 Correct 19 ms 35796 KB Output is correct
23 Correct 19 ms 35724 KB Output is correct
24 Correct 19 ms 35788 KB Output is correct
25 Correct 19 ms 35708 KB Output is correct
26 Correct 20 ms 35648 KB Output is correct
27 Correct 23 ms 35668 KB Output is correct
28 Incorrect 20 ms 35580 KB Breaking single line is causing network to disconnect.
29 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 35484 KB Output is correct
2 Correct 21 ms 35540 KB Output is correct
3 Correct 19 ms 35544 KB Output is correct
4 Correct 19 ms 35540 KB Output is correct
5 Correct 19 ms 35524 KB Output is correct
6 Correct 18 ms 35528 KB Output is correct
7 Correct 18 ms 35540 KB Output is correct
8 Correct 20 ms 35408 KB Output is correct
9 Correct 18 ms 35548 KB Output is correct
10 Correct 18 ms 35540 KB Output is correct
11 Correct 18 ms 35552 KB Output is correct
12 Correct 18 ms 35540 KB Output is correct
13 Correct 17 ms 35548 KB Output is correct
14 Correct 19 ms 35508 KB Output is correct
15 Correct 20 ms 35452 KB Output is correct
16 Correct 19 ms 35540 KB Output is correct
17 Correct 18 ms 35552 KB Output is correct
18 Correct 18 ms 35452 KB Output is correct
19 Correct 17 ms 35496 KB Output is correct
20 Correct 20 ms 35544 KB Output is correct
21 Correct 16 ms 35540 KB Output is correct
22 Correct 19 ms 35796 KB Output is correct
23 Correct 19 ms 35724 KB Output is correct
24 Correct 19 ms 35788 KB Output is correct
25 Correct 19 ms 35708 KB Output is correct
26 Correct 20 ms 35648 KB Output is correct
27 Correct 23 ms 35668 KB Output is correct
28 Incorrect 20 ms 35580 KB Breaking single line is causing network to disconnect.
29 Halted 0 ms 0 KB -