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 == 0)
        {
            printf("1\n");
            continue;
        }
        int a,b,i;
        for(i =0;i<= MAXN;i++)
        {
            p[i] = i;
            ans[i] =1;
        }
        for(i = 0; i < n ;i++)
        {
            scanf("%d%d",&a, &b);
            merg(a,b);
        }
        int max = 0;
        for(i =0 ;i<=MAXN;i++)
        {
            max = MAX(max, ans[i]);
        }
        printf("%d\n",max);
    }
    return 0;
}