UVa247 Calling Circles (Floyd,DFS)

Posted 2020-08-09

链接：http://bak3.vjudge.net/problem/UVA-247

分析：先用Floyd求出有向图的传递闭包，然后用DFS求出各个联通分量即可。

 

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <vector>
 4 #include <string>
 5 using namespace std;
 6 
 7 vector<string> names;
 8 int ID(const string& s) {
 9     for (int i = 0; i < names.size(); i++)
10         if (names[i] == s) return i;
11     names.push_back(s);
12     return names.size() - 1;
13 }
14 
15 const int maxn = 25 + 5;
16 int n, m;
17 int vis[maxn];
18 int d[maxn][maxn];
19 void dfs(int u) {
20     vis[u] = 1;
21     for (int v = 0; v < n; v++)
22         if (!vis[v] && d[u][v] && d[v][u]) {
23             printf(", %s", names[v].c_str());
24             dfs(v);
25         }
26 }
27 
28 int main() {
29     int kase = 0;
30     char s1[99], s2[99];
31     while (scanf("%d%d", &n, &m) == 2 && n) {
32         names.clear();
33         memset(d, 0, sizeof(d));
34         for (int i = 0; i < n; i++) d[i][i] = 1;
35         while (m--) {
36             scanf("%s%s", s1, s2);
37             d[ID(s1)][ID(s2)] = 1;
38         }
39         for (int k = 0; k < n; k++)
40             for (int i = 0; i < n; i++)
41                 for (int j = 0; j < n; j++)
42                     d[i][j] |= d[i][k] && d[k][j];
43         if (kase > 0) printf("\n");
44         printf("Calling circles for data set %d:\n", ++kase);
45         memset(vis, 0, sizeof(vis));
46         for (int i = 0; i < n; i++)
47             if (!vis[i]) {
48                 printf("%s", names[i].c_str());
49                 dfs(i);
50                 printf("\n");
51             }
52     }
53     return 0;
54 }