不相交集

 1 public class DisjoinSet 
 2 {
 3 
 4     public static void main(String[] args)
 5     {
 6         DisjoinSet disjoin = new DisjoinSet(8);
 7 
 8         disjoin.union(4, 3);
 9         disjoin.union(5, 4);
10         disjoin.union(6, 5);
11         disjoin.union(7, 6);
12         disjoin.union(8, 7);
13         
14         int c = disjoin.find(3);
15         disjoin.display();
16     }
17     
18     
19     private int n;
20     
21     private int[] parents;
22     
23     private int[] rank;
24     
25     
26     public DisjoinSet(int n)
27     {
28         this.n = n;
29         init();
30     }
31 
32     private void init()
33     {
34         parents = new int[n + 1];
35         rank = new int[n + 1];
36         
37         for (int i = 1; i <= n; i++) {
38             parents[i] = i;
39             rank[i] = i;
40         }
41     }
42     
43     public int find(int x)
44     {
45         int parent = x;
46         while (parent != parents[parent]) {
47             parent = parents[parent];
48         }
49         
50         disjoin(x, parent);
51         return parent;
52     }
53     
54     private void disjoin(int x, int parent)
55     {
56         int temp;
57         while (x != parent) {
58             temp = parents[x];
59             parents[x] = parent;
60             x = temp;
61         }
62     }
63     
64     public void union(int a, int b)
65     {
66         int compare = compare(rank[a], rank[b]); 
67         if (compare == 1) {
68             parents[b] = a;
69         }
70         else {
71             parents[a] = b;
72         }
73     }
74     
75     private int compare(int a, int b)
76     {
77         return a > b ? 1 : a < b ? -1 : 0;
78     }
79     
80     public void display()
81     {
82         for (int i : rank) {
83             System.out.print(" " + i + " ");
84         }
85         
86         System.out.println();
87         
88         for (int i : parents) {
89             System.out.print(" " + i + " ");
90         }
91     }
92 }