POJ1611(The Suspects)--简单并查集

题目在这里

关于SARS病毒传染的问题。在同一个组的学生是接触很近的，后面也会有新的同学的加入。其中有一位同学感染SARS，那么该组的所有同学得了SARS。要计算出有多少位学生感染SARS了。编号为0的同学是得了SARS的。

直接用并查集解决水掉

 #include<iostream>
 #include<stdio.h>
 #include<cstring>
 #include<cmath>
 #include<vector>
 #include<stack>
 #include<map>
 #include<set>
 #include<list>
 #include<queue>
 #include<string>
 #include<algorithm>
 #include<iomanip>
 using namespace std;
 #define MAX 100

 struct node
 {
     int no;//编号
     int rank;
     int parent;
     int total;
 };

 class DisJoinSet
 {
     protected:
         int n;
         node * tree;
     public:
         DisJoinSet(int n );
         ~DisJoinSet();
         void Init();
         void Union(int x,int y);
         int Find(int x);
         int GetAswer(int x);
 };

 DisJoinSet ::DisJoinSet(int  n)//初始化操作
 {
     this->n = n;
     tree = new node[n];
     for(int i =  ; i < n; i++)
     {
         tree[i].no = i;
         tree[i].parent = i;
         tree[i].total = ;
         tree[i].rank = ;
     }
 }
 DisJoinSet::~DisJoinSet()
 {
     delete[] tree;
 }

 void DisJoinSet :: Init()
 {
 }
 int DisJoinSet::Find(int x)
 {
     int temp = tree[x].parent;//temp 为x的父亲结点
     if( x != tree[x].parent)
     {
         tree[x].parent = Find(tree[x].parent);//路径压缩
         return tree[x].parent;
     }
     else
     {
         return x;
     }
 }

 void DisJoinSet ::Union(int x,int y)
 {
     int rootx = Find(x);
     int rooty = Find(y);
     if(rootx == rooty)
     {
         return ;
     }
     else//并查集基本操作
     {
         if(tree[rootx].rank < tree[rooty].rank)
         {
             tree[rootx].parent = rooty;
             tree[rooty].total += tree[rootx].total;
         }
         else
         {
             tree[rooty].parent = rootx;
             tree[rootx].total += tree[rooty].total;
             if(tree[rootx].rank == tree[rooty].rank)
             {
                 tree[rootx].rank++;
             }
         }
     }
 }

 int DisJoinSet::GetAswer(int x)//返回xtotal
 {
     int t = Find(x);
     return tree[t].total;
 }

 int main()
 {
     int n;
     int m;
     while(cin>>n>>m && n!= && m>= )
     {
         DisJoinSet dis(n);
         int per1;
         int per2;
         for(int i = ; i< m;i++)
         {
             int num = ;
             cin>>num;
             cin>>per1;
             for(int i =  ;i < num; i++)
             {
                 cin>>per2;
                 dis.Union(per1,per2);
             }
         }
         cout<<dis.GetAswer()<<endl;
     }
     return ;
 }