POJ 2524 Ubiquitous Religions(並查集)

//並查集的簡單應用——帶路徑壓縮的並查集<br />//平攤分析後，每個點只需遍曆一次即可建立相應並查集，搜尋的複雜度是O(1);<br />//計算不相交集合的個數<br />#include<iostream><br />using namespace std;<br />int fa[50010],n,m,ans,vis[50010];<br />void initSet()//初始化<br />{<br />for(int i = 1;i <= n;++i)<br />fa[i] = i;<br />}<br />int Find(int x)<br />{<br />int temp_x = x;<br />if(x == fa[x])return x;<br />else return fa[x] = Find(fa[x]);//路徑壓縮並查集<br />}<br />void Union(int x,int y)<br />{<br />x = Find(x);<br />y = Find(y);<br />if(x != y)fa[x] = y;<br />}</p><p>int main()<br />{<br />//freopen("in.txt","r",stdin);<br />int x,y,caseN = 0;<br />while(scanf("%d%d",&n,&m) && n)<br />{<br />ans = 0;<br />initSet();<br />memset(vis,0,sizeof(vis));<br />while(m--)<br />{<br />scanf("%d%d",&x,&y);<br />Union(x,y);<br />}<br />for(int i = 1;i <= n;++i)<br />{<br />if(!vis[Find(i)])<br />{<br />++ans;<br />vis[Find(i)] = 1;<br />}<br />}<br />printf("Case %d: %d/n",++caseN,ans);<br />}<br />return 0;<br />}