HDU 1811 并查集

题意：

思路：topo+并查集

 #include <cstdio>
 #include <vector>
 #include <algorithm>
 #include <queue>
 #include <iostream>
 using namespace std;
 vector<int > web[];
 int p[],n,m,sum,f[],A[],B[];
 char C[];
 bool ok;
 int find(int x) {return p[x] == x ? x : p[x] = find(p[x]);}
 void order(){
     queue<int> q;
     for ( int i =  ; i < n ; ++i)
         if ( f[i] ==  && find(i) == i )
             q.push(i);
     while(!q.empty()){
         if ( q.size() > ) ok=true;///否则说明信息不完全
         int cur = q.front();
         q.pop();
         sum--;
         for(int i =  ; i < web[cur].size() ; ++i)
         {
             if(--f[web[cur][i]]==)
                 q.push(web[cur][i]);
         }
     }
     return ;
 }
 int main(){
     while (scanf("%d %d",&n,&m) != EOF){
         ok = false ;sum = n;
         for (int i =  ;i <= n;++i){
             p[i] = i;
             web[i].clear();
             f[i] =  ;
         }
         for (int i =  ;i < m; ++i){
             scanf("%d %c %d",&A[i],&C[i],&B[i]);
             int x = find(A[i]),y = find(B[i]);
             if (C[i] == '='){
                 if (x != y){
                     p[y] = x;
                     sum--;
                 }
             }
         }
         for (int i =  ;i < m;++i){
             if (C[i] == '=') continue;
             int x = find(A[i]);
             int y = find(B[i]);
             if (C[i] == '>'){
                 web[x].push_back(y);
                 f[y]++;
             }
             else {
                 web[y].push_back(x);
                 f[x]++;
             }
         }
         order();
         if (sum > )  printf("CONFLICT\n");
         else if (ok)  printf("UNCERTAIN\n");
         else printf("OK\n");
     }
     return ;
 }