并查集2

并查集的实现代码及解析：

public class UnionFind {
    public static class Element<V> {
        public V value;
        
        public Element(V value) {
            this.value = value;
        }
    }
    
    public static class UnionFindSet<V> {
        public HashMap<V,Element<V>> elementMap;
        public HashMap<Element<V>,Element<V>> fatherMap;
        public HashMap<Element<V>,Integer> sizeMap;
        
        public UnionFindSet(List<V> list) {
            elementMap = new HashMap<>();
            fatherMap = new HashMap<>();
            sizeMap = new HashMap<>();
            for (V value : list) {
                Element<V> element = new Element<>(value);
                elementMap.put(value,element);
                fatherMap.put(element,element);
                sizeMap.put(element,1);
            }
        }
        
        public Element<V> find(Element<V> element) {
            Stack<Element<V>> sk = new Stack<>();
            while (element != fatherMap.get(element)) {
                sk.push(element);
                element = fatherMap.get(element);
            }
            //将同一个集合节点的父亲统一
            while (!sk.empty()) {
                fatherMap.put(sk.pop(), element);
            }
            return element;
        }
        
        public boolean isSameSet(V a,V b) {
            if (elementMap.containsKey(a) && elementMap.containsKey(b)) {
                return find(elementMap.get(a)) == find(elementMap.get(b));
            }
            return false;
        }
        
        public void union(V a,V b) {
            Element<V> aF = elementMap.get(a);
            Element<V> bF = elementMap.get(b);
            
            if (aF != bF) {//不在同一组的情况下才要进行合并操作
                Element<V> big = sizeMap.get(find(aF)) >= sizeMap.get(find(bF)) ? aF : bF;
                Element<V> small = big == aF ? bF : aF;
                fatherMap.put(small, big);
                sizeMap.put(big, sizeMap.get(small) + sizeMap.get(big));
                sizeMap.remove(small);
            }
        }
    }
}