http://acm.hdu.edu.cn/showproblem.php?pid=1811
1 #include <stdio.h> 2 #include <string.h> 3 #include <queue> 4 #include <vector> 5 using namespace std; 6 const int N=200010; 7 vector<int>V[N]; 8 queue<int>q; 9 char oper[N]; 10 int in[N],f[N]; 11 int a[N],b[N]; 12 int n,m,sum; 13 void init() 14 { 15 sum = n; 16 while(!q.empty()) q.pop(); 17 for (int i = 0; i <= n; i++) 18 { 19 f[i] = i; 20 in[i] = 0; 21 V[i].clear(); 22 } 23 } 24 int Find(int x) 25 { 26 if(x!=f[x]) return f[x]=Find(f[x]); 27 return x; 28 } 29 int Merge(int x,int y) 30 { 31 x = Find(x); 32 y = Find(y); 33 if(x!=y) 34 { 35 f[y] = x; 36 return 1; 37 } 38 return 0; 39 } 40 void toposort() 41 { 42 int flag = 0; 43 for (int i = 0; i < n; i++) 44 { 45 if(in[i]==0&&Find(i)==i) 46 q.push(i); 47 } 48 while(!q.empty()) 49 { 50 if (q.size()>1)flag = 1; 51 int u = q.front(); 52 q.pop(); 53 sum--; 54 for (int i = 0 ; i < V[u].size(); i++) 55 { 56 if(--in[V[u][i]]==0) 57 q.push(V[u][i]); 58 } 59 } 60 if (sum > 0) printf("CONFLICT "); 61 else if (flag) printf("UNCERTAIN "); 62 else printf("OK "); 63 } 64 int main() 65 { 66 while(~scanf("%d%d",&n,&m)) 67 { 68 init(); 69 int u,v; 70 for (int i = 0; i < m; i++) 71 { 72 scanf("%d %c %d",&a[i],&oper[i],&b[i]); 73 if(oper[i]=='=') 74 { 75 if(Merge(a[i],b[i])) 76 sum--; 77 } 78 } 79 for (int i = 0; i < m; i++) 80 { 81 if(oper[i]=='=') continue; 82 u = Find(a[i]); 83 v = Find(b[i]); 84 if(oper[i]=='>') 85 { 86 V[u].push_back(v); 87 in[v]++; 88 } 89 if(oper[i]=='<') 90 { 91 V[v].push_back(u); 92 in[u]++; 93 } 94 } 95 toposort(); 96 } 97 return 0; 98 }