题解 | #二叉树的后序遍历#
二叉树的后序遍历
http://www.nowcoder.com/practice/1291064f4d5d4bdeaefbf0dd47d78541
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 { /** * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可 * * * @param root TreeNode类 * @return int整型一维数组 */ public int[] postorderTraversal (TreeNode root) { if (root == null) { return new int[0]; } List<Integer> list = new ArrayList<>(); bfs(root, list); int[] array = list.stream().mapToInt(Integer::intValue).toArray(); return array; } private void bfs(TreeNode node, List<Integer> list) { if (node.left != null) { bfs(node.left, list); } if (node.right != null) { bfs(node.right, list); } list.add(node.val); } }