uva10305

Posted 2020-09-14 yijiull

题目连接：https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=1246

拓扑排序

lrj167

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<set>
 4 #include<iostream>
 5 #include<cctype>
 6 #include<string>
 7 #include<sstream>
 8 #include<algorithm>
 9 #include<map>
10 #define LL long long
11 using namespace std;
12 const int maxn=110;
13 int u,v;
14 int n,m;
15 int t;
16 int top[maxn],vis[maxn];
17 int p[maxn][maxn];
18 int  dfs(int u)
19 {
20     vis[u]=-1;
21     for(int v=1;v<=n;v++) if(p[u][v])
22     {
23         if(vis[v]<0) return 0;
24         else if(!vis[v]&&!dfs(v)) return 0;
25     }
26     vis[u]=1;
27     top[t--]=u;
28     return 1;
29 }
30 int main()
31 {
32     while(scanf("%d%d",&n,&m)&&(n||m))
33     {
34         memset(p,0,sizeof(p));
35         memset(vis,0,sizeof(vis));
36         for(int i=0;i<m;i++)
37         {
38             scanf("%d%d",&u,&v);
39             p[u][v]=1;
40         }
41         t=n;
42         for(int i=1;i<=n;i++) if(!vis[i])
43             dfs(i);
44         for(int i=1;i<n;i++)
45             printf("%d ",top[i]);
46         printf("%d\n",top[n]);
47     }
48 }