[LintCode] Connecting Graph III

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(), Returns the number of connected component in the graph

 

Example

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

class UnionFind {
    private int[] father = null;
    private int count = 0;
    public UnionFind(int n){
        father = new int[n];
        count = n;
        for(int i = 0; i < n; i++){
            father[i] = i;
        }
    }
    public int find(int x){
        if(father[x] == x){
            return x;
        }
        return father[x] = find(father[x]);
    }
    public void connect(int a, int b){
        int root_a = find(a);
        int root_b = find(b);
        if(root_a != root_b){
            father[root_a] = root_b;
            count--;
        }
    }
    public int queryUnionCount(){
        return count;
    }
}
public class ConnectingGraph3 {
    private UnionFind uf = null;
    public ConnectingGraph3(int n) {
        uf = new UnionFind(n);        
    }

    public void connect(int a, int b) {
        uf.connect(a - 1, b - 1);
    }
        
    public int query() {
        return uf.queryUnionCount();
    }
}