poj 2524(并查集)

package com.liang.poj;

import java.util.Scanner;

public class Main {
	static int n = 0;
	static int m = 0;
	static int[] node = null;
	static int[] childNum = null;
	static int count = 0;
	static int sum = 0;
	
	public static void main(String[] args) throws Exception {
		Scanner scan = new Scanner(System.in);
		while (scan.hasNext()) {
			n = scan.nextInt();
			m = scan.nextInt();
			
			if(n == 0 || m == 0) {
				break;
			}
			
			node = new int[n + 1];
			childNum = new int[n + 1];
			
			makeSet();

			for (int i = 1; i <= m; i++) {
				int a = scan.nextInt();
				int b = scan.nextInt();
				merge(a, b);
			}

			for (int i = 1; i <= n; i++) {
				if (node[i] == i) {
					sum++;
				}
			}
			
			System.out.println("Case "+ ++count + ": " + sum);
		}
	}

	public static void makeSet() {
		sum = 0;
		for (int i = 1; i <= n; i++) {
			node[i] = i;
			childNum[i] = 0;
		}
	}

	public static int findFather(int x) {
		if (x != node[x]) {
			x = findFather(node[x]);
		}
		return x;
	}

	public static void merge(int a, int b) {
		int fa = findFather(a);
		int fb = findFather(b);
		if (fa != fb) {
			if (childNum[fa] >= childNum[fb]) {
				node[fb] = fa;
				childNum[fa]++;
			} else {
				node[fa] = fb;
				childNum[fb]++;
			}
		}

	}

}