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题目描述
从上往下打印出二叉树的每个节点,同层节点从左至右打印
题目链接:https://www.nowcoder.com/practice/7fe2212963db4790b57431d9ed259701
解题思路
取出每层每个节点,输出值同时存储存在的左右子节点,进而进行层序遍历
public class Solution {
public ArrayList<Integer> PrintFromTopToBottom(TreeNode root) {
ArrayList<TreeNode> list = new ArrayList<>();
ArrayList<Integer> result = new ArrayList<>();
if (root == null) return result;
list.add(root);
while (list.size() != 0) {
TreeNode node = list.remove(0);
result.add(node.val);
if (node.left != null) list.add(node.left);
if (node.right != null) list.add(node.right);
}
return result;
}
}