-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathUnionFind5.java
More file actions
65 lines (50 loc) · 1.39 KB
/
UnionFind5.java
File metadata and controls
65 lines (50 loc) · 1.39 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
package union;
/**
* 基于rank优化
*/
public class UnionFind5 implements UF{
private int[] parent;
private int[] rank; // rank[i]表示以i为根的集合中表示的数的高度
public UnionFind5(int size){
parent = new int[size];
rank = new int[size];
for (int i = 0; i < size; i++) {
parent[i] = i;
rank[i] = 1;
}
}
// p == parent[p] 是一个根节点
private int find(int p) {
if (p < 0 || p >= parent.length) {
throw new IllegalArgumentException("Index is illegal");
}
if (p != parent[p]) {
// 递归版本路径压缩 所有节点指向根节点
parent[p] = find(parent[p]);
}
return parent[p];
}
@Override
public int getSize() {
return parent.length;
}
@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);
// 根据rank决定合并方向
if (rank[pRoot] < rank[qRoot]){
parent[pRoot] = qRoot;
}else if (rank[pRoot] > rank[qRoot]){
parent[qRoot] = pRoot;
}else {
// 高度相等的时候 需要加1
parent[qRoot] = pRoot;
rank[pRoot] += 1;
}
}
}