blob: aab4fb4ae699dca348b5fe10318c5419276d1834 (
plain)
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
|
/*
* Quick Union algorithm
*
* Slightly better than quickfind
*
* treats each element in the array as a node in a tree and trees may be
* connected together or not. Essentially each element might be its own tree.
*
* Find: Check if p and q have the same root
*
* Union. Merge components containing p and q, set the id of p's root to the id
* of q's root.
*
* Still too slow though. Trees can get too tall, where the worst case is a tree
* where one element points to a single one until the end of the tree,
* essentially creating an array.
*/
public class QuickUnionUF {
private int[] id;
/* Constructor */
public QuickUnionUF(int N) {
id = new int[N];
for (int i = 0; i < N; i++)
id[i] = i;
}
/* Return root of 'i' */
private int root(int i) {
while (i != id[i])
i = id[i];
return i;
}
/* Are the objects connected */
public boolean connected(int p, int q) {
return root(p) == root(q);
}
/* Connect two objects */
public void union(int p, int q) {
int proot = root(p);
id[proot] = root(q);
}
}
|
