1 #include <cstdio> 2 #include <cstring> 3 #include <iostream> 4 using namespace std; 5  6 int caseNum,citizen,pairNum; 7 typedef struct node{ 8     int data_;//节点对应人的编号 9     int rank_;//节点对应的秩10     int parent_;//节点对应双亲下标11 }UFSTree;12 void MAKE_SET(UFSTree t[]);//初始化并查集树13 int FIND_SET(UFSTree t[],int x);//在x所在子树中查找集合编号14 void UNION(UFSTree t[],int x,int y);//将x和y所在的子树合并15 int main()16 {17     //freopen("D:\\acm.txt","r",stdin);18     int maxNum;19     cin>>caseNum;20         for(int cycle = 0;cycle < caseNum;cycle++){21             cin>>citizen>>pairNum;22             maxNum = 0;23             UFSTree t[30011];24             MAKE_SET(t);25             for(int m = 0;m < pairNum;m++){26                 int x,y;27                 cin>>x>>y;28                 UNION(t,x,y);29             }30             for(int op = 1;op <= citizen;op++){31                 if(maxNum < t[op].rank_)maxNum = t[op].rank_;32             }33             cout<<maxNum<<endl;34         }35     return 0;36 }37 void MAKE_SET(UFSTree t[]){38     for(int i = 1;i <= citizen;i++){39         t[i].data_ = i;//数据为该人编号40         t[i].rank_ = 1;41         t[i].parent_ = i;//父节点指向自己42     }43 }44 int FIND_SET(UFSTree t[],int x){45     if(x != t[x].parent_){46         return (FIND_SET(t,t[x].parent_));47     }48     else49         return x;50 }51 void UNION(UFSTree t[],int x,int y){52     x = FIND_SET(t,x);53     y = FIND_SET(t,y);54     if(x==y)return;55     if(t[x].rank_ > t[y].rank_){56             t[y].parent_ = x;57             t[x].rank_ += t[y].rank_;58     }59     else{60         t[x].parent_ = y;61         t[y].rank_ += t[x].rank_;62     }63 }