题解 | #把二叉树打印成多行#

import java.util.ArrayList;


/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    ArrayList<ArrayList<Integer> > Print(TreeNode pRoot) {
        ArrayList<ArrayList<Integer> > res = new ArrayList<ArrayList<Integer> >();
        ArrayList<Integer> list = new ArrayList<Integer>();
        // pRoot为空
        if(pRoot == null){
            return res;
        }
        // pRoot不为空
        ArrayList<TreeNode> tList = new ArrayList<TreeNode>();
        TreeNode temp = null; // 指针
        tList.add(pRoot);
        int size = 0;
        while(tList.size() != 0){
            size = tList.size();
            for(int i = 0;i < size;i++){
                temp = tList.remove(0);
                if(temp.left != null){
                    tList.add(temp.left);
                }
                if(temp.right != null){
                    tList.add(temp.right);
                }
                list.add(temp.val);
            }
            res.add(new ArrayList<Integer>(list));
            list.clear();
        }
        return res;
    }
}