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ID题目提交者结果用时内存语言文件大小提交时间测评时间
#72227#3846. Link-Cut Treeneko_nyaa#AC ✓217ms22460kbC++231.9kb2023-01-15 10:23:152023-01-15 10:23:18

Judging History

你现在查看的是最新测评结果

  • [2023-08-10 23:21:45]
  • System Update: QOJ starts to keep a history of the judgings of all the submissions.
  • [2023-01-15 10:23:18]
  • 评测
  • 测评结果:AC
  • 用时:217ms
  • 内存:22460kb
  • [2023-01-15 10:23:15]
  • 提交

answer

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

#define int long long

struct DSU {
	vector<int> P, S;
	DSU(int n) {
		P.resize(n+1);
		S.resize(n+1, 1);
		for (int i = 1; i <= n; i++) P[i] = i;
	}
	
	int find(int x) {
		if (x == P[x]) return x;
		return P[x] = find(P[x]);
	}
	
	bool merge(int a, int b) {
		a = find(a); b = find(b);
		if (a == b) return 0;
		if (S[a] < S[b]) swap(a, b);
		
		S[a] += S[b];
		P[b] = a;
		return 1;
	}
	
	int same(int a, int b) {
		return find(a) == find(b);
	}
};

int par[100001], pid[100001], hei[100001];
vector<pair<int, int>> adj[100001];

void dfs(int now, int prv, int h, int pri) {
	hei[now] = h;
	par[now] = prv;
	pid[now] = pri;

	for (auto [u, i]: adj[now]) {
		if (u != prv) {
			dfs(u, now, h+1, i);
		}
	}
}

void solve() {
	int n, m; cin >> n >> m;
	DSU d(n); vector<tuple<int, int, int>> e;
	bool f = 0;
	for (int i = 1; i <= m; i++) {
		int x, y; cin >> x >> y;
		if (f) continue;
		e.emplace_back(x, y, i);
		if (!d.merge(x, y)) f = 1;
	}
	if (!f) {
		cout << "-1\n";
		return;
	}

	auto [p, q, id1] = e.back(); e.pop_back();
	for (int i = 1; i <= n; i++) {
		adj[i].clear(); par[i] = hei[i] = pid[i] = 0;
	}
	for (auto [u, v, i]: e) {
		adj[u].emplace_back(v, i);
		adj[v].emplace_back(u, i);
	}

	for (int i = 1; i <= n; i++) {
		if (par[i] == 0) {
			dfs(i, i, 1, 0);
		}
	}

	vector<int> ans; ans.push_back(id1);
	if (hei[p] < hei[q]) swap(p, q);
	while (hei[p] > hei[q]) {
		ans.push_back(pid[p]);
		p = par[p];
	} 

	while (p != q) {
		ans.push_back(pid[p]);
		p = par[p];
		ans.push_back(pid[q]);
		q = par[q];
	}

	sort(ans.begin(), ans.end());
	for (int i = 0; i < ans.size(); i++) {
		cout << ans[i];
		if (i+1 == ans.size()) {
			cout << "\n";
		} else {
			cout << ' ';
		}
	}
}

signed main() {
	ios::sync_with_stdio(0); cin.tie(0);

	int t; cin >> t;
	while (t--) {
		solve();
	}

	return 0;
}

詳細信息

Test #1:

score: 100
Accepted
time: 2ms
memory: 6744kb

input:

2
6 8
1 2
2 3
5 6
3 4
2 5
5 4
5 1
4 2
4 2
1 2
4 3

output:

2 4 5 6
-1

result:

ok 2 lines

Test #2:

score: 0
Accepted
time: 217ms
memory: 21404kb

input:

1658
9 20
6 4
5 8
1 7
2 3
3 8
3 1
4 8
5 3
7 6
1 6
4 9
4 1
9 3
2 5
4 5
8 9
1 8
4 2
5 7
3 6
14 78
13 12
10 8
2 10
6 13
2 14
13 1
14 10
9 6
2 13
8 3
9 8
5 6
14 12
8 1
9 14
9 5
12 6
5 10
3 12
10 4
8 5
9 10
6 8
1 6
12 4
3 13
1 5
10 3
13 9
10 13
2 5
4 7
7 1
7 6
9 3
2 12
1 10
9 1
1 14
3 1
3 4
11 1
11 6
7 1...

output:

2 5 8
3 5 7
1 3 4
2 3 4
2 3 4 7 13
1 3 4 5 9
3 4 7 12
1 2 3
8 10 11
2 3 5 7 12 13 14 15 16
1 2 3 5
1 2 4
1 3 4
1 2 3
1 2 3
10 11 15
1 5 6
1 5 7
1 2 3 4
-1
1 3 6
-1
1 2 3 5
-1
-1
6 8 9 10 11 16
1 2 6
2 3 4
-1
-1
7 8 12 13 18
-1
1 4 8 12
3 5 10
4 6 8
1 2 3 4
3 5 6
5 8 10 15
4 6 8
-1
1 2 3 5 6
1 3 4
1 ...

result:

ok 1658 lines

Test #3:

score: 0
Accepted
time: 213ms
memory: 22460kb

input:

10
100000 100000
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
10 11
11 12
12 13
13 14
14 15
15 16
16 17
17 18
18 19
19 20
20 21
21 22
22 23
23 24
24 25
25 26
26 27
27 28
28 29
29 30
30 31
31 32
32 33
33 34
34 35
35 36
36 37
37 38
38 39
39 40
40 41
41 42
42 43
43 44
44 45
45 46
46 47
47 48
48 49
49 50
50 51
...

output:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 ...

result:

ok 10 lines