美团层序打印多叉树

public class Main1 {

    public static void main(String args[])
    {
    	Scanner in = new Scanner(System.in);
    	//保存根节点到直接子元素的映射
    	Map<Integer, Integer[]> map = new HashMap<Integer, Integer[]>();
    	//根节点
    	int root = 0;
    	boolean first = true;
    	
    	while (in.hasNext()) {
    		String line = in.nextLine();
    		String[] s = line.split("\\s");
    		//解析字符串到整数
    		Integer[] ints = new Integer[s.length];
    		for (int i = 0; i < s.length; i++) {
    			ints[i] = Integer.parseInt(s[i]);
    		}
    		
    		if (first) {
    			//保存根节点
    			root = ints[0];
    			first = false;
    		}
    		map.put(ints[0], ints);
    	}
    	
    	//层序遍历
    	Queue<Integer> q = new LinkedList<Integer>();
    	q.add(root);
    	while (!q.isEmpty()) {
    		int r = q.remove();
    		System.out.print(r + " ");
    		Integer[] nodes = map.get(r);
    		if (nodes != null) {
    			for (int i = 1; i < nodes.length; i++) {
    				q.add(nodes[i]);
    			}
    		}
    	}
    	
    }
}