用树实现的并查集
接口
public interface UF{
int getSize();
boolean isConnected(int p,int q);
void unionElements(int p,int q);
}
public class UnionFindV6 implements UF{
private int[] parent;
private int[] rank;
/**
* 构造函数
*/
public UnionFindV6 (int size) {
parent = new int[size];
rank = new int[size];
for (int i = 0; i < size; i++) {
parent[i] = i;
rank[i] = 1;
}
}
@Override
public int getSize() {
return parent.length;
}
private int find(int p) {
if (p < 0 && p >= parent.length) {
throw new IllegalArgumentException("p is out of bound");
}
if (p != parent[p]) {
parent[p] = find(parent[p]);
}
return parent[p];
}
@Override
public boolean isConnected(int p, int q) {
return find(p) == find(q);
}
@Override
public void unionElements(int p, int q) {
int pRoot = find(p);
int qRoot = find(q);
if (pRoot == qRoot) {
return;
}
if (rank[pRoot] < rank[qRoot]) {
parent[pRoot] = qRoot;
} else if (rank[pRoot] > rank[qRoot]) {
parent[qRoot] = pRoot;
} else {
parent[qRoot] = pRoot;
rank[pRoot] += 1;
}
}
}