HDU1856More is better(并查集)

最近发现以前的东西都忘得差不多了，在这里刷刷水题

并查集：

 int find_parent(int x)
 {
     return x = p[x] ? x : p[x] = find_parent(p[x]);
 }

 void merg(int a,int b)
 {
     int x = find_parent(a);
     int y = find_parent(b);
     if(x != y)
     {
         p[x] = y;
     }
 }

 #include<iostream>
 #include<stdio.h>
 #include<string.h>
 #include<map>
 #include<vector>
 #include<set>
 #include<stack>
 #include<queue>
 #include<algorithm>
 #include<stdlib.h>
 using namespace std;
 #define MAX(a,b) (a > b ? a : b)
 #define MIN(a,b) (a < b ? a : b)
 #define MAXN  10000001
 #define INF 2000000007
 #define mem(a) memset(a,0,sizeof(a))

 int p[MAXN];
 int ans[MAXN];

 int find(int x)
 {
     return x==p[x]? x : p[x] = find(p[x]);
 }

 void merg(int a, int b)
 {
     int x = find(a);
     int y = find(b);
     if(x != y)
     {
         p[x] = y;
         ans[y] +=ans[x];
     }
 }

 int main()
 {
     int n;
     while(~scanf("%d", &n))
     {
         if(n == )
         {
             printf("1\n");
             continue;
         }
         int a,b,i;
         for(i =;i<= MAXN;i++)
         {
             p[i] = i;
             ans[i] =;
         }
         for(i = ; i < n ;i++)
         {
             scanf("%d%d",&a, &b);
             merg(a,b);
         }
         int max = ;
         for(i = ;i<=MAXN;i++)
         {
             max = MAX(max, ans[i]);
         }
         printf("%d\n",max);
     }
     return ;
 }