场景

刷题的时候，二叉树类型的题目，用里面的示例数据无法快速构建入参进行测试，顾封装了一个工具类。

代码demo

@Slf4j
@Data
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;}TreeNode left(int val){this.left = new TreeNode(val);return this;}TreeNode right(int val){this.right = new TreeNode(val);return this;}private static final String NULL = "null";/*** 构造树* @param nodes* @return*/public static TreeNode buildTree(Integer[] nodes){if (nodes.length == 0 || (nodes.length == 1 && Objects.isNull(nodes[0]))){return null;}TreeNode root = new TreeNode(nodes[0]);Queue<TreeNode> queue = new LinkedList<>();queue.offer(root);int pos = 1;while(!queue.isEmpty() && pos < nodes.length){TreeNode node = queue.poll();if (Objects.nonNull(nodes[pos])){node.left = new TreeNode(nodes[pos]);queue.offer(node.left);}pos++;if (pos == nodes.length){break;}if (Objects.nonNull(nodes[pos])){node.right = new TreeNode(nodes[pos]);queue.offer(node.right);}pos++;}return root;}public static void printTree(TreeNode root){if (root == null){log.info("[]");return;}StringBuilder builder = new StringBuilder();builder.append("[");Queue<TreeNode> queue = new LinkedList<>();boolean allEmpty = false;int size;queue.offer(root);while (!queue.isEmpty() && !allEmpty){allEmpty = true;size = queue.size();while (size > 0){size--;TreeNode node = queue.poll();if (node == null){builder.append(NULL).append(CommonConstants.COMMA);queue.offer(null);queue.offer(null);}else {builder.append(node.getVal()).append(CommonConstants.COMMA);queue.offer(node.left);queue.offer(node.right);if (node.left != null || node.right != null){allEmpty = false;}}}}builder.replace(builder.length()-1, builder.length(), "]");log.info("{}", builder);}public static void main(String[] args) {Integer[] nodes = {4,1,6,0,2,5,7,null,null,null,3,null,null,null,8};TreeNode root = buildTree(nodes);}/*** 获得最左元素 如果是二叉搜索树即最小元素* @param root* @return*/public static TreeNode getLeftest(TreeNode root){if (root == null){return null;}TreeNode item = root, result = item;while(true){if (item.left != null){item = item.left;result = item;}else if (item.right != null){item = item.right;}else {return result;}}}/*** 校验两棵树是否一样* @param p* @param q* @return*/public static boolean sameCheck(TreeNode p, TreeNode q){if (Objects.isNull(p) && Objects.isNull(q)){return true;}if (Objects.isNull(p) || Objects.isNull(q) || p.getVal() != q.getVal()){return false;}return sameCheck(p.getLeft(), q.getLeft()) && sameCheck(p.getRight(), q.getRight());}/*** 根据字符串值构造数据* @param s* @return*/public static TreeNode constructNode(String s){if (NULL.equals(s)){return null;}return new TreeNode(Integer.parseInt(s));}}