转自：wutianqi http://www.wutianqi.com/?p=1069
tag：并查集
#include <iostream>
using namespace std; #define MAX 10000001 // father[x]表示x的父节点
int father[MAX];
// rank[x]表示x的秩
int rank[MAX]; // 初始化
void Make_Set(int n)
{
for(int i=; i<=n; ++i)
{
father[i] = i;
rank[i] = ;
}
} // 查找
int Find_Set(int x)
{
if(x != father[x])
return Find_Set(father[x]);
return x;
} // 合并
void Union(int x, int y)
{
x = Find_Set(x);
y = Find_Set(y);
if(x == y) // x,y在同一个集合
return;
if(rank[x] > rank[y])
{
father[y] = x;
rank[x] += rank[y];
}
else if(rank[x] < rank[y])
{
father[x] = y;
rank[y] += rank[x];
}
else
{
father[x] = y;
//rank[y]++;
rank[y] += rank[x];
} } int main()
{
//freopen("input.txt", "r", stdin);
int a, b;
int nNum;
while(scanf("%d", &nNum) != EOF)
{
Make_Set(MAX);
if(nNum==)
{
printf("1\n");
continue;
}
for(int i=; i<nNum; ++i)
{
scanf("%d %d", &a, &b);
Union(a, b);
//printf("rank[%d]=%d rank[%d]=%d\n", a, rank[a], b, rank[b]);
}
int _max=;
for(int i=; i<=MAX; ++i)
//printf("%d ", rank[i]);
if(_max < rank[i])
_max = rank[i];
printf("%d\n", _max);
}
return ;
}