题解 | #把二叉树打印成多行#

二叉树层次遍历

import java.util.*;
/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;
    public TreeNode(int val) {
        this.val = val;
    }
}
*/
public class Solution {
    ArrayList > Print(TreeNode pRoot) {
        ArrayList> res = new ArrayList();
        if(pRoot == null){
            return res;
        }
        Queue q = new LinkedList(); 
        q.add(pRoot);
        while(!q.isEmpty()){
            int size = q.size();
            ArrayList temp = new ArrayList();
            for(int i=0;i<size;i++){
                TreeNode node = q.poll();
                temp.add(node.val);
                if(node.left != null){
                    q.add(node.left);
                }
                if(node.right != null){
                    q.add(node.right);
                }
            }
            res.add(temp);
        }
        return res;
    }

}