http://acm.hdu.edu.cn/showproblem.php?pid=1856
More is better
Time Limit: 5000/1000 MS (Java/Others) Memory Limit: 327680/102400 K (Java/Others)
Total Submission(s): 18767 Accepted Submission(s): 6896
Mr Wang selected a room big enough to hold the boys. The boy who are not been chosen has to leave the room immediately. There are 10000000 boys in the room numbered from 1 to 10000000 at the very beginning. After Mr Wang's selection any two of them who are still in this room should be friends (direct or indirect), or there is only one boy left. Given all the direct friend-pairs, you should decide the best way.
1 2
3 4
5 6
1 6
4
1 2
3 4
5 6
7 8
2
A and B are friends(direct or indirect), B and C are friends(direct or indirect),
then A and C are also friends(indirect).
In the first sample {1,2,5,6} is the result.
In the second sample {1,2},{3,4},{5,6},{7,8} are four kinds of answers.
#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
#define N 100010
int F[N];
int G[N];
int Gf(int t)
{
if(F[t]==-) return t;
F[t] = Gf(F[t]);
return F[t];
}
int mx;
void bing (int a , int b)
{
int fa = Gf(a);
int fb = Gf(b);
if(fa!=fb)
{
F[fa] = fb;
G[fb] += G[fa];
mx = max(mx,G[fb]);
}
}
int main()
{
int n;
while(~scanf("%d",&n))
{
mx = ;
memset(F,-,sizeof(F));
for(int i = ;i <= N ;i++)
{
G[i] = ;
}
for(int i = ;i < n ;i++)
{
int a , b;
scanf("%d%d",&a,&b);
bing (a, b);
}
printf("%d\n",mx);
}
return ;
}