UVa 10305 Ordering Tasks【拓扑排序】

题意：给出n件事情，m个二元组关系，求它们的拓扑序列

 

用的队列来做

 1 #include<iostream>  

 2 #include<cstdio>  

 3 #include<cstring> 

 4 #include <cmath> 

 5 #include<stack>

 6 #include<vector>

 7 #include<map> 

 8 #include<set>

 9 #include<queue> 

10 #include<algorithm>  

11 using namespace std;

12 

13 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)

14 

15 typedef long long LL;

16 const int INF = (1<<30)-1;

17 const int mod=1000000007;

18 const int maxn=100005;

19 int ecnt;

20 int n,m;

21 

22 int g[1005][1005],in[1005],ans[maxn];

23 

24 void toposort(){

25     queue<int> q;

26     

27     for(int i=1;i<=n;i++)

28     if(in[i]==0) q.push(i);

29     

30     int cnt=0;

31     while(!q.empty()){

32         int tmp=q.front();q.pop();

33         ans[++cnt]=tmp;

34         

35         for(int j=1;j<=n;j++){

36             if(g[tmp][j]){

37                 in[j]--;

38                 if(in[j]==0) q.push(j);

39             }

40         }        

41     }

42     

43     printf("%d",ans[1]);

44     for(int i=2;i<=cnt;i++)

45     printf(" %d",ans[i]);    

46     printf("\n");

47 }

48 

49 

50 int main(){

51     while(scanf("%d %d",&n,&m)!=EOF){

52         if(n==0&&m==0) break;

53         

54         memset(g,0,sizeof(g));

55         memset(in,0,sizeof(in));

56         

57         while(m--){

58             int u,v;

59             cin>>u>>v;

60             g[u][v]=1;

61             in[v]++;

62         }

63         toposort();

64     }

65     return 0;        

66 }

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