[LintCode] Connecting Graph II

Posted 2020-10-14 Push your limit!

Given n nodes in a graph labeled from 1 to n. There is no edges in the graph at beginning.

You need to support the following method:
1. connect(a, b), an edge to connect node a and node b
2. query(a), Returns the number of connected component nodes which include node a.

 

 

Example

5 // n = 5
query(1) return 1
connect(1, 2)
query(1) return 2
connect(2, 4)
query(1) return 3
connect(1, 4)
query(1) return 3

 1 class UnionFind {
 2     private int[] father = null;
 3     private int[] numsInUnion = null;
 4     
 5     public UnionFind(int n){
 6         father = new int[n];
 7         numsInUnion = new int[n];
 8         for(int i = 0; i < n; i++){
 9             father[i] = i;
10             numsInUnion[i] = 1;
11         }
12     }
13     public int find(int x){
14         if(father[x] == x){
15             return x;
16         }
17         return father[x] = find(father[x]);
18     }
19     public void connect(int a, int b){
20         int root_a = find(a);
21         int root_b = find(b);
22         if(root_a != root_b){
23             father[root_a] = root_b;
24             numsInUnion[root_b] += numsInUnion[root_a];
25         }
26     }
27     public int queryNumInUnion(int a){
28         return numsInUnion[find(a)];
29     }
30 }
31 public class ConnectingGraph2 {
32     private UnionFind uf = null;
33     public ConnectingGraph2(int n) {
34         uf = new UnionFind(n);
35     }
36 
37     public void connect(int a, int b) {
38         uf.connect(a - 1, b - 1);
39     }
40         
41     public int query(int a) {
42         return uf.queryNumInUnion(a - 1);
43     }
44 }