并查集详解
https://blog.csdn.net/sjystone/article/details/115406797

搭配购买 https://www.acwing.com/problem/content/1254/

并查集和01背包问题结合

将一组云放入一个集合中，在每个集合的跟节点维护该集合的价钱和价值，即体积和重量
用01背包解法遍历每一个跟节点

#include <iostream>
using namespace std;

const int N = 10010;
int f[N], w[N], v[N], n, m, vol, p[N];

int find(int x)
{
    if ( x != p[x] ) p[x] = find(p[x]);
    return p[x];
}

int main()
{
    cin >> n >> m >> vol;
    for ( int i = 1; i <= n; i ++ ) 
    {
        cin >> v[i] >> w[i];
        p[i] = i;
    }
    while ( m -- )
    {
        int a, b;
        cin >> a >> b;
        int pa = find(a), pb = find(b);
        if ( pa != pb )
        {
            v[pb] += v[pa];
            w[pb] += w[pa];
            p[pa] = pb;
        }
    }
    for ( int i = 1; i <= n; i ++ )
        if ( i == p[i] ) 
            for ( int j = vol; j >= v[i]; j -- )
                f[j] = max(f[j], f[j - v[i]] + w[i]);
    cout << f[vol];
    return 0;
}