劍指 Offer - 22:從上往下列印二叉樹
阿新 • • 發佈:2018-12-18
題目描述
從上往下打印出二叉樹的每個節點,同層節點從左至右列印
題目連結:https://www.nowcoder.com/practice/7fe2212963db4790b57431d9ed259701
解題思路
取出每層每個節點,輸出值同時儲存存在的左右子節點,進而進行層序遍歷
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;
}
}