拓扑排序

hdu 1811 Rank of Tetris 

注意一些特殊情况View Code 
 1 #include<iostream>
 2 #include<cstdio>
 3 #include<vector>
 4 #include<cstring>
 5 #include<cmath>
 6 #include<queue>
 7 #include<cstdlib>
 8 #include<algorithm>
 9 using namespace std;
10 const int MAX=110000;
11 const int INF=100000000;
12 int f[MAX],into[MAX],vis[MAX];
13 int n,m;
14 vector<int> G[MAX];
15 queue<int> q;
16 int ans;
17 int find(int x){
18     if(x==f[x]) return x;
19     return f[x]=find(f[x]);
20 }
21 void TopologicalSort() {
22     ans=0; int sum=0; 
23     if(!q.empty()) q.pop();
24     for(int i=0;i<n;i++){
25         if(!into[f[i]]&&f[i]==i){
26             q.push(f[i]);
27         }
28     }
29     memset(vis,0,sizeof(vis));
30     while(!q.empty()){
31         if(q.size()>1) ans=1;
32         int u=q.front(); q.pop();
33         vis[u]=1;
34         for (int k=0;k<G[u].size();k++){
35             int v=G[u][k]; 
36             into[v]--;
37             if(!into[v]){
38                 q.push(v);
39             }
40         }
41     }
42     for(int i=0;i<n;i++) if(!vis[f[i]]) { ans=2; return ;}
43 }
44 struct node{
45     int x,y;
46     char s;
47 };
48 int main(){
49     while(scanf("%d%d",&n,&m)!=EOF){
50         for(int i=0;i<n;i++) {
51             f[i]=i;
52             G[i].clear();
53         }
54         vector<node> v;
55         node B;
56         memset(into, 0, sizeof(into));
57         for(int i=0;i<m;i++){
58             char s[5]; int x,y;
59             scanf("%d%s%d",&x,s,&y);    
60             int rx=find(x),ry=find(y);
61             if(s[0]=='=') f[ry]=rx;
62             else {
63                 B.x=x; B.y=y; B.s=s[0];
64                 v.push_back(B);
65             }
66         }
67         for(int i=0;i<n;i++) f[i]=find(i);
68         for(int i=0;i<v.size();i++){
69             int x=f[v[i].x],y=f[v[i].y];
70             if(v[i].s=='>'&&
71                 find(G[x].begin(),G[x].end(),y)==G[x].end())
72                 G[x].push_back(y),into[y]++;
73             if(v[i].s=='<'&&
74                 find(G[y].begin(),G[y].end(),x)==G[y].end())
75                 G[y].push_back(x),into[x]++;
76         }
77         TopologicalSort();
78         if(ans==0) printf("OK\n");
79         if(ans==1) printf("UNCERTAIN\n");
80         if(ans==2) printf("CONFLICT\n");
81     }
82 }



posted @ 2012-03-10 14:03  HaoHua_Lee  阅读(99)  评论(0)  编辑  收藏  举报