/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode() {} * TreeNode(int val) { this.val = val; } * TreeNode(int val, TreeNode left, TreeNode right) { * this.val = val; * this.left = left; * this.right = right; * } * } */ class Solution { public TreeNode addOneRow(TreeNode root, int v, int d) { if(d == 1){ TreeNode newNode = new TreeNode(v); newNode.left = root; return newNode; } Queue qu = new LinkedList<>(); d = d-1; qu.offer(root); int level = 1; while(level != d){ int size = qu.size(); level++; while(size-->0){ TreeNode head =qu.poll(); if(head.left!=null){ qu.offer(head.left); } if(head.right!=null){ qu.offer(head.right); } } } while(!qu.isEmpty()){ TreeNode head = qu.poll(); TreeNode leftChild = head.left; TreeNode rightChild = head.right; TreeNode newLeft = new TreeNode(v); TreeNode newRight = new TreeNode(v); head.left = newLeft; head.right = newRight; newLeft.left = leftChild; newRight.right = rightChild; } return root; } }