public List<List<Integer>> levelOrder(TreeNode root) { Queue<TreeNode> queue = new LinkedList<>(); List<List<Integer>> res = new ArrayList<>(); if (root != null) { queue.add(root); } while (!queue.isEmpty()){ List<Integer> temp = new ArrayList<>(); // The layering here is very beautiful for (int i = queue.size(); i > 0; i--){ TreeNode t = queue.poll(); temp.add(t.val); if (t.left != null){ queue.add(t.left); } if (t.right != null){ queue.add(t.right); } } res.add(temp); } return res; }
Sword refers to Offer-31 print binary tree from top to bottom II
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Origin blog.csdn.net/a792396951/article/details/113844400
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