【Tarjan】P1726 上白泽慧音

 1 #include<iostream>
 2 #include<stack>
 3 #include<vector>
 4 #include<algorithm>
 5 using namespace std;
 6 
 7 int n, m;
 8 int dfn[5010], low[5010];
 9 bool vis[5010];
10 stack<int>s;
11 int cnt;
12 vector<int>to[5010];
13 int ans;
14 int tot;
15 int res[100010];
16 int num[100010];
17 
18 void tarjan(int x)
19 {
20     dfn[x] = low[x] = ++cnt;
21     s.push(x);
22     vis[x] = true;
23     for (int i = 0; i < to[x].size(); i++)
24     {
25         if (!dfn[to[x][i]])
26         {
27             tarjan(to[x][i]);
28             low[x] = min(low[x], low[to[x][i]]);
29         }
30         else if(vis[to[x][i]])
31         {
32             low[x] = min(low[x], dfn[to[x][i]]);
33         }
34     }
35     if (low[x] == dfn[x])
36     {
37         tot++;
38         while (!s.empty() && s.top() != x)
39         {
40             int t = s.top();
41             res[t] = tot;
42             num[tot]++;
43             vis[t] = false;
44             s.pop();
45         };
46         s.pop();
47         res[x] = tot;
48         num[tot]++;
49         vis[x] = false;
50     }
51 }
52 
53 int main()
54 {
55     cin >> n >> m;
56     for (int i = 1; i <= m; i++)
57     {
58         int f, a, b;
59         cin >> a >> b >> f;
60         to[a].push_back(b);
61         if (f == 2) to[b].push_back(a);
62     }
63     for (int i = 1; i <= n; i++)
64     {
65         if (!dfn[i]) tarjan(i);
66     }
67     for (int i = 1; i <= tot; i++) 
68         ans = max(ans, num[i]);
69     cout << ans << endl;
70     int mark = 0;
71     for (int i = 1; i <= n; i++)
72     {
73         if (!mark && num[res[i]] == ans) mark = res[i];
74         if (num[res[i]] == ans && mark == res[i])
75         {
76             cout << i << " ";
77         }
78     }
79     return 0;
80 }

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