【poj 1182】 食物链　题解＆代码（Ｃ＋＋）

#include<iostream>
#include<string.h>
#include<stdio.h>
using namespace std;
int fa[509999];
inline void chushihua(int n)
{
for (int i=1;i<=n;i++)  fa[i]=i;
}
int find(int x)
{
if (fa[x]==x)   return x;
return fa[x]=find(fa[x]);
}
int unio(int x,int y)
{
return fa[find(x)]=find(y);
}
int main()
{
int n,m,a,b,c;
scanf("%d%d",&n,&m);
chushihua(3*n);
int ans=0;
for (int i=1;i<=m;i++)
{
scanf("%d%d%d",&a,&b,&c);
if (b>n || c>n || (a==2&&b==c) || b<=0 || c<=0)
{ans++;continue;}
if (a==1)
{
if (find(b)!=find(c) && find(c+n)!=find(b) && find(c+2*n)!=find(b) && find(c)!=find(b+n) &&find(c)!=find(b+n+n))
{
unio(b,c);
unio(b+n,c+n);
unio(b+2*n,c+2*n);
}
else if (find(b)==find(c))  continue;
else if (find(b)!=find(c) && (find(c+n)==find(b) || find(c+2*n)==find(b) || find(c)==find(b+n) || find(c)==find(b+n+n)))    ans++;
}
else if (a==2)
{
if (find(b)==find(c) || find(c)==find(b+n))
{ans++;continue;}
else {
unio(c+n,b);
unio(b+2*n,c);
unio(b+n,c+n+n);
}
}
}
cout<<ans<<endl;
}