20140711 eat

 1 #include<cstdio> 
 2  
 3 const int N = 100005; 
 4 int n, m, f[N], rank[N]; 
 5  
 6 inline void init(){ 
 7     for(int i=0; i<=n; ++i) 
 8         f[i]=i,rank[i]=0; 
 9 } 
10  
11 int find(int x){ 
12     if(x==f[x])return x; 
13     int fa=f[x]; 
14     f[x]=find(f[x]); 
15     rank[x] = (rank[x]+rank[fa])%3; 
16     return f[x]; 
17 } 
18  
19 inline bool Union(int x,int y,int D){ 
20     int a=find(x), b=find(y); 
21     if(a==b){ 
22         if(D==1&&rank[x]!=rank[y]) return false; 
23         if(D==2){ 
24             if(rank[x]==2&&rank[y]!=1)return false; 
25             if(rank[x]==1&&rank[y]!=0)return false; 
26             if(rank[x]==0&&rank[y]!=2)return false; 
27         } 
28         return true; 
29     } 
30     f[a] = b; 
31     if(D==2){ 
32         rank[a] = (rank[y]-rank[x]+3+1)%3; 
33     } 
34     else{ 
35         rank[a] = (rank[y]-rank[x]+3)%3;   
36     } 
37     return true; 
38 } 
39  
40 int main(){ 
41     freopen("eat.in","r",stdin);
42     freopen("eat.out","w",stdout);
43     int x,y,d; 
44     scanf("%d%d",&n,&m); 
45     init(); 
46     int cnt=0; 
47     for(int i=0; i<m; ++i){ 
48         scanf("%d%d%d",&d,&x,&y); 
49         if(x>n || y>n || d==2&&x==y){ 
50             ++cnt; continue; 
51         } 
52         if(!Union(x,y,d)) { 
53             ++cnt; 
54         } 
55     } 
56     printf("%d\n",m-cnt); 
57     return 0; 
58 }