## 树

| \# | 题名 | 题解 | 通过率 | 难度 | 出现频率   |
|------|----------------------|-----|--------|----|--------|
|834|[树中距离之和](https://leetcode-cn.com/problems/sum-of-distances-in-tree)   |[7](https://leetcode-cn.com/problems/sum-of-distances-in-tree/solution)|30.7%|困难|59.4%|
|333|[最大 BST 子树](https://leetcode-cn.com/problems/largest-bst-subtree)   |[18](https://leetcode-cn.com/problems/largest-bst-subtree/solution)|40.6%|中等|52.31%|
|426|[将二叉搜索树转化为排序的双向链表](https://leetcode-cn.com/problems/convert-binary-search-tree-to-sorted-doubly-linked-list)   |[16](https://leetcode-cn.com/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/solution)|57.6%|中等|49.85%|
|124|[二叉树中的最大路径和](https://leetcode-cn.com/problems/binary-tree-maximum-path-sum)   |[71](https://leetcode-cn.com/problems/binary-tree-maximum-path-sum/solution)|38.4%|困难|47.24%|
|536|[从字符串生成二叉树](https://leetcode-cn.com/problems/construct-binary-tree-from-string)   |[6](https://leetcode-cn.com/problems/construct-binary-tree-from-string/solution)|47.2%|中等|45.53%|
|199|[二叉树的右视图](https://leetcode-cn.com/problems/binary-tree-right-side-view)   |[83](https://leetcode-cn.com/problems/binary-tree-right-side-view/solution)|62.2%|中等|42.79%|
|543|[二叉树的直径](https://leetcode-cn.com/problems/diameter-of-binary-tree)   |[42](https://leetcode-cn.com/problems/diameter-of-binary-tree/solution)|46.4%|简单|40.94%|
|889|[根据前序和后序遍历构造二叉树](https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal)   |[9](https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal/solution)|61.4%|中等|36.02%|
|428|[序列化和反序列化 N 叉树](https://leetcode-cn.com/problems/serialize-and-deserialize-n-ary-tree)   |[13](https://leetcode-cn.com/problems/serialize-and-deserialize-n-ary-tree/solution)|65.5%|困难|36.02%|
|652|[寻找重复的子树](https://leetcode-cn.com/problems/find-duplicate-subtrees)   |[16](https://leetcode-cn.com/problems/find-duplicate-subtrees/solution)|52.2%|中等|35.31%|
|94|[二叉树的中序遍历](https://leetcode-cn.com/problems/binary-tree-inorder-traversal)   |[132](https://leetcode-cn.com/problems/binary-tree-inorder-traversal/solution)|69.3%|中等|35.31%|
|662|[二叉树最大宽度](https://leetcode-cn.com/problems/maximum-width-of-binary-tree)   |[20](https://leetcode-cn.com/problems/maximum-width-of-binary-tree/solution)|34.4%|中等|35.2%|
|226|[翻转二叉树](https://leetcode-cn.com/problems/invert-binary-tree)   |[122](https://leetcode-cn.com/problems/invert-binary-tree/solution)|73.0%|简单|34.74%|
|450|[删除二叉搜索树中的节点](https://leetcode-cn.com/problems/delete-node-in-a-bst)   |[44](https://leetcode-cn.com/problems/delete-node-in-a-bst/solution)|37.0%|中等|34.38%|
|297|[二叉树的序列化与反序列化](https://leetcode-cn.com/problems/serialize-and-deserialize-binary-tree)   |[43](https://leetcode-cn.com/problems/serialize-and-deserialize-binary-tree/solution)|42.9%|困难|34.29%|
|236|[二叉树的最近公共祖先](https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-tree)   |[63](https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-tree/solution)|58.7%|中等|34.07%|
|654|[最大二叉树](https://leetcode-cn.com/problems/maximum-binary-tree)   |[70](https://leetcode-cn.com/problems/maximum-binary-tree/solution)|78.1%|中等|32.6%|
|572|[另一个树的子树](https://leetcode-cn.com/problems/subtree-of-another-tree)   |[42](https://leetcode-cn.com/problems/subtree-of-another-tree/solution)|42.4%|简单|31.42%|
|105|[从前序与中序遍历序列构造二叉树](https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal)   |[79](https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/solution)|63.2%|中等|31.4%|
|776|[拆分二叉搜索树](https://leetcode-cn.com/problems/split-bst)   |[10](https://leetcode-cn.com/problems/split-bst/solution)|50.2%|中等|30.66%|
|102|[二叉树的层次遍历](https://leetcode-cn.com/problems/binary-tree-level-order-traversal)   |[147](https://leetcode-cn.com/problems/binary-tree-level-order-traversal/solution)|60.0%|中等|30.45%|
|663|[均匀树划分](https://leetcode-cn.com/problems/equal-tree-partition)   |[7](https://leetcode-cn.com/problems/equal-tree-partition/solution)|39.7%|中等|30.03%|
|103|[二叉树的锯齿形层次遍历](https://leetcode-cn.com/problems/binary-tree-zigzag-level-order-traversal)   |[121](https://leetcode-cn.com/problems/binary-tree-zigzag-level-order-traversal/solution)|52.8%|中等|29.44%|
|104|[二叉树的最大深度](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree)   |[198](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree/solution)|71.5%|简单|29.42%|
|1123|[最深叶节点的最近公共祖先](https://leetcode-cn.com/problems/lowest-common-ancestor-of-deepest-leaves)   |[17](https://leetcode-cn.com/problems/lowest-common-ancestor-of-deepest-leaves/solution)|61.6%|中等|29.14%|
|96|[不同的二叉搜索树](https://leetcode-cn.com/problems/unique-binary-search-trees)   |[66](https://leetcode-cn.com/problems/unique-binary-search-trees/solution)|64.0%|中等|29%|
|101|[对称二叉树](https://leetcode-cn.com/problems/symmetric-tree)   |[153](https://leetcode-cn.com/problems/symmetric-tree/solution)|49.2%|简单|28.18%|
|114|[二叉树展开为链表](https://leetcode-cn.com/problems/flatten-binary-tree-to-linked-list)   |[80](https://leetcode-cn.com/problems/flatten-binary-tree-to-linked-list/solution)|66.5%|中等|27.91%|
|515|[在每个树行中找最大值](https://leetcode-cn.com/problems/find-largest-value-in-each-tree-row)   |[26](https://leetcode-cn.com/problems/find-largest-value-in-each-tree-row/solution)|56.9%|中等|27.59%|
|449|[序列化和反序列化二叉搜索树](https://leetcode-cn.com/problems/serialize-and-deserialize-bst)   |[14](https://leetcode-cn.com/problems/serialize-and-deserialize-bst/solution)|49.6%|中等|27.51%|
|95|[不同的二叉搜索树 II](https://leetcode-cn.com/problems/unique-binary-search-trees-ii)   |[55](https://leetcode-cn.com/problems/unique-binary-search-trees-ii/solution)|60.5%|中等|27.1%|
|863|[二叉树中所有距离为 K 的结点](https://leetcode-cn.com/problems/all-nodes-distance-k-in-binary-tree)   |[26](https://leetcode-cn.com/problems/all-nodes-distance-k-in-binary-tree/solution)|44.6%|中等|27.09%|
|1130|[叶值的最小代价生成树](https://leetcode-cn.com/problems/minimum-cost-tree-from-leaf-values)   |[15](https://leetcode-cn.com/problems/minimum-cost-tree-from-leaf-values/solution)|55.2%|中等|26.77%|
|110|[平衡二叉树](https://leetcode-cn.com/problems/balanced-binary-tree)   |[99](https://leetcode-cn.com/problems/balanced-binary-tree/solution)|49.4%|简单|26.69%|
|545|[二叉树的边界](https://leetcode-cn.com/problems/boundary-of-binary-tree)   |[11](https://leetcode-cn.com/problems/boundary-of-binary-tree/solution)|34.3%|中等|26.53%|
|1008|[先序遍历构造二叉树](https://leetcode-cn.com/problems/construct-binary-search-tree-from-preorder-traversal)   |[24](https://leetcode-cn.com/problems/construct-binary-search-tree-from-preorder-traversal/solution)|71.0%|中等|26.29%|
|958|[二叉树的完全性检验](https://leetcode-cn.com/problems/check-completeness-of-a-binary-tree)   |[25](https://leetcode-cn.com/problems/check-completeness-of-a-binary-tree/solution)|46.1%|中等|26.29%|
|106|[从中序与后序遍历序列构造二叉树](https://leetcode-cn.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal)   |[54](https://leetcode-cn.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/solution)|65.8%|中等|25.15%|
|1026|[节点与其祖先之间的最大差值](https://leetcode-cn.com/problems/maximum-difference-between-node-and-ancestor)   |[12](https://leetcode-cn.com/problems/maximum-difference-between-node-and-ancestor/solution)|55.3%|中等|24.98%|
|144|[二叉树的前序遍历](https://leetcode-cn.com/problems/binary-tree-preorder-traversal)   |[96](https://leetcode-cn.com/problems/binary-tree-preorder-traversal/solution)|63.0%|中等|23.86%|
|701|[二叉搜索树中的插入操作](https://leetcode-cn.com/problems/insert-into-a-binary-search-tree)   |[25](https://leetcode-cn.com/problems/insert-into-a-binary-search-tree/solution)|70.8%|中等|23.72%|
|108|[将有序数组转换为二叉搜索树](https://leetcode-cn.com/problems/convert-sorted-array-to-binary-search-tree)   |[97](https://leetcode-cn.com/problems/convert-sorted-array-to-binary-search-tree/solution)|68.1%|简单|23.51%|
|617|[合并二叉树](https://leetcode-cn.com/problems/merge-two-binary-trees)   |[72](https://leetcode-cn.com/problems/merge-two-binary-trees/solution)|74.3%|简单|23.29%|
|145|[二叉树的后序遍历](https://leetcode-cn.com/problems/binary-tree-postorder-traversal)   |[96](https://leetcode-cn.com/problems/binary-tree-postorder-traversal/solution)|69.2%|困难|22.06%|
|968|[监控二叉树](https://leetcode-cn.com/problems/binary-tree-cameras)   |[12](https://leetcode-cn.com/problems/binary-tree-cameras/solution)|35.2%|困难|21.74%|
|112|[路径总和](https://leetcode-cn.com/problems/path-sum)   |[100](https://leetcode-cn.com/problems/path-sum/solution)|48.4%|简单|21.58%|
|637|[二叉树的层平均值](https://leetcode-cn.com/problems/average-of-levels-in-binary-tree)   |[45](https://leetcode-cn.com/problems/average-of-levels-in-binary-tree/solution)|62.1%|简单|21.5%|
|988|[从叶结点开始的最小字符串](https://leetcode-cn.com/problems/smallest-string-starting-from-leaf)   |[17](https://leetcode-cn.com/problems/smallest-string-starting-from-leaf/solution)|41.9%|中等|21.36%|
|298|[二叉树最长连续序列](https://leetcode-cn.com/problems/binary-tree-longest-consecutive-sequence)   |[9](https://leetcode-cn.com/problems/binary-tree-longest-consecutive-sequence/solution)|53.0%|中等|20.7%|
|222|[完全二叉树的节点个数](https://leetcode-cn.com/problems/count-complete-tree-nodes)   |[35](https://leetcode-cn.com/problems/count-complete-tree-nodes/solution)|64.2%|中等|20.52%|
|337|[打家劫舍 III](https://leetcode-cn.com/problems/house-robber-iii)   |[52](https://leetcode-cn.com/problems/house-robber-iii/solution)|54.9%|中等|20.2%|
|99|[恢复二叉搜索树](https://leetcode-cn.com/problems/recover-binary-search-tree)   |[44](https://leetcode-cn.com/problems/recover-binary-search-tree/solution)|54.1%|困难|19.98%|
|1245|[树的直径](https://leetcode-cn.com/problems/tree-diameter)   |[7](https://leetcode-cn.com/problems/tree-diameter/solution)|39.6%|中等|19.89%|
|107|[二叉树的层次遍历 II](https://leetcode-cn.com/problems/binary-tree-level-order-traversal-ii)   |[111](https://leetcode-cn.com/problems/binary-tree-level-order-traversal-ii/solution)|63.5%|简单|19.4%|
|230|[二叉搜索树中第K小的元素](https://leetcode-cn.com/problems/kth-smallest-element-in-a-bst)   |[80](https://leetcode-cn.com/problems/kth-smallest-element-in-a-bst/solution)|67.4%|中等|19.39%|
|437|[路径总和 III](https://leetcode-cn.com/problems/path-sum-iii)   |[61](https://leetcode-cn.com/problems/path-sum-iii/solution)|53.0%|简单|19.28%|
|606|[根据二叉树创建字符串](https://leetcode-cn.com/problems/construct-string-from-binary-tree)   |[36](https://leetcode-cn.com/problems/construct-string-from-binary-tree/solution)|51.5%|简单|19.18%|
|255|[验证前序遍历序列二叉搜索树](https://leetcode-cn.com/problems/verify-preorder-sequence-in-binary-search-tree)   |[11](https://leetcode-cn.com/problems/verify-preorder-sequence-in-binary-search-tree/solution)|44.9%|中等|19.03%|
|938|[二叉搜索树的范围和](https://leetcode-cn.com/problems/range-sum-of-bst)   |[73](https://leetcode-cn.com/problems/range-sum-of-bst/solution)|75.5%|简单|18.47%|
|530|[二叉搜索树的最小绝对差](https://leetcode-cn.com/problems/minimum-absolute-difference-in-bst)   |[29](https://leetcode-cn.com/problems/minimum-absolute-difference-in-bst/solution)|54.8%|简单|18.37%|
|559|[N叉树的最大深度](https://leetcode-cn.com/problems/maximum-depth-of-n-ary-tree)   |[44](https://leetcode-cn.com/problems/maximum-depth-of-n-ary-tree/solution)|67.5%|简单|17.95%|
|111|[二叉树的最小深度](https://leetcode-cn.com/problems/minimum-depth-of-binary-tree)   |[110](https://leetcode-cn.com/problems/minimum-depth-of-binary-tree/solution)|40.8%|简单|17.82%|
|687|[最长同值路径](https://leetcode-cn.com/problems/longest-univalue-path)   |[19](https://leetcode-cn.com/problems/longest-univalue-path/solution)|38.0%|简单|17.1%|
|98|[验证二叉搜索树](https://leetcode-cn.com/problems/validate-binary-search-tree)   |[131](https://leetcode-cn.com/problems/validate-binary-search-tree/solution)|28.1%|中等|16.91%|
|897|[递增顺序查找树](https://leetcode-cn.com/problems/increasing-order-search-tree)   |[25](https://leetcode-cn.com/problems/increasing-order-search-tree/solution)|64.0%|简单|16.42%|
|113|[路径总和 II](https://leetcode-cn.com/problems/path-sum-ii)   |[84](https://leetcode-cn.com/problems/path-sum-ii/solution)|57.9%|中等|16.09%|
|501|[二叉搜索树中的众数](https://leetcode-cn.com/problems/find-mode-in-binary-search-tree)   |[34](https://leetcode-cn.com/problems/find-mode-in-binary-search-tree/solution)|42.6%|简单|15.78%|
|404|[左叶子之和](https://leetcode-cn.com/problems/sum-of-left-leaves)   |[70](https://leetcode-cn.com/problems/sum-of-left-leaves/solution)|52.8%|简单|15.52%|
|685|[冗余连接 II](https://leetcode-cn.com/problems/redundant-connection-ii)   |[12](https://leetcode-cn.com/problems/redundant-connection-ii/solution)|32.5%|困难|15.34%|
|979|[在二叉树中分配硬币](https://leetcode-cn.com/problems/distribute-coins-in-binary-tree)   |[10](https://leetcode-cn.com/problems/distribute-coins-in-binary-tree/solution)|64.3%|中等|15.04%|
|257|[二叉树的所有路径](https://leetcode-cn.com/problems/binary-tree-paths)   |[81](https://leetcode-cn.com/problems/binary-tree-paths/solution)|61.2%|简单|14.87%|
|513|[找树左下角的值](https://leetcode-cn.com/problems/find-bottom-left-tree-value)   |[48](https://leetcode-cn.com/problems/find-bottom-left-tree-value/solution)|67.4%|中等|13.69%|
|116|[填充每个节点的下一个右侧节点指针](https://leetcode-cn.com/problems/populating-next-right-pointers-in-each-node)   |[58](https://leetcode-cn.com/problems/populating-next-right-pointers-in-each-node/solution)|51.2%|中等|13.43%|
|429|[N叉树的层序遍历](https://leetcode-cn.com/problems/n-ary-tree-level-order-traversal)   |[60](https://leetcode-cn.com/problems/n-ary-tree-level-order-traversal/solution)|63.8%|中等|13.42%|
|538|[把二叉搜索树转换为累加树](https://leetcode-cn.com/problems/convert-bst-to-greater-tree)   |[50](https://leetcode-cn.com/problems/convert-bst-to-greater-tree/solution)|57.5%|简单|13.37%|
|235|[二叉搜索树的最近公共祖先](https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-search-tree)   |[70](https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-search-tree/solution)|61.3%|简单|13.35%|
|270|[最接近的二叉搜索树值](https://leetcode-cn.com/problems/closest-binary-search-tree-value)   |[25](https://leetcode-cn.com/problems/closest-binary-search-tree-value/solution)|49.0%|简单|13.3%|
|589|[N叉树的前序遍历](https://leetcode-cn.com/problems/n-ary-tree-preorder-traversal)   |[42](https://leetcode-cn.com/problems/n-ary-tree-preorder-traversal/solution)|71.1%|简单|11.77%|
|129|[求根到叶子节点数字之和](https://leetcode-cn.com/problems/sum-root-to-leaf-numbers)   |[60](https://leetcode-cn.com/problems/sum-root-to-leaf-numbers/solution)|60.3%|中等|11.56%|
|894|[所有可能的满二叉树](https://leetcode-cn.com/problems/all-possible-full-binary-trees)   |[13](https://leetcode-cn.com/problems/all-possible-full-binary-trees/solution)|72.9%|中等|11.36%|
|508|[出现次数最多的子树元素和](https://leetcode-cn.com/problems/most-frequent-subtree-sum)   |[17](https://leetcode-cn.com/problems/most-frequent-subtree-sum/solution)|59.6%|中等|11.28%|
|100|[相同的树](https://leetcode-cn.com/problems/same-tree)   |[148](https://leetcode-cn.com/problems/same-tree/solution)|55.8%|简单|10.88%|
|563|[二叉树的坡度](https://leetcode-cn.com/problems/binary-tree-tilt)   |[21](https://leetcode-cn.com/problems/binary-tree-tilt/solution)|51.4%|简单|10.79%|
|653|[两数之和 IV - 输入 BST](https://leetcode-cn.com/problems/two-sum-iv-input-is-a-bst)   |[33](https://leetcode-cn.com/problems/two-sum-iv-input-is-a-bst/solution)|52.6%|简单|10.45%|
|173|[二叉搜索树迭代器](https://leetcode-cn.com/problems/binary-search-tree-iterator)   |[57](https://leetcode-cn.com/problems/binary-search-tree-iterator/solution)|69.6%|中等|10.28%|
|783|[二叉搜索树结点最小距离](https://leetcode-cn.com/problems/minimum-distance-between-bst-nodes)   |[41](https://leetcode-cn.com/problems/minimum-distance-between-bst-nodes/solution)|51.1%|简单|9.63%|
|582|[杀死进程](https://leetcode-cn.com/problems/kill-process)   |[18](https://leetcode-cn.com/problems/kill-process/solution)|31.8%|中等|9.62%|
|814|[二叉树剪枝](https://leetcode-cn.com/problems/binary-tree-pruning)   |[24](https://leetcode-cn.com/problems/binary-tree-pruning/solution)|71.4%|中等|7.74%|
|993|[二叉树的堂兄弟节点](https://leetcode-cn.com/problems/cousins-in-binary-tree)   |[40](https://leetcode-cn.com/problems/cousins-in-binary-tree/solution)|49.2%|简单|7.26%|
|669|[修剪二叉搜索树](https://leetcode-cn.com/problems/trim-a-binary-search-tree)   |[25](https://leetcode-cn.com/problems/trim-a-binary-search-tree/solution)|63.3%|简单|6.2%|
|872|[叶子相似的树](https://leetcode-cn.com/problems/leaf-similar-trees)   |[36](https://leetcode-cn.com/problems/leaf-similar-trees/solution)|61.4%|简单|5.97%|
|684|[冗余连接](https://leetcode-cn.com/problems/redundant-connection)   |[35](https://leetcode-cn.com/problems/redundant-connection/solution)|54.6%|中等|5.91%|
|117|[填充每个节点的下一个右侧节点指针 II](https://leetcode-cn.com/problems/populating-next-right-pointers-in-each-node-ii)   |[47](https://leetcode-cn.com/problems/populating-next-right-pointers-in-each-node-ii/solution)|43.1%|中等|3.87%|
|590|[N叉树的后序遍历](https://leetcode-cn.com/problems/n-ary-tree-postorder-traversal)   |[37](https://leetcode-cn.com/problems/n-ary-tree-postorder-traversal/solution)|71.2%|简单|3.59%|
|700|[二叉搜索树中的搜索](https://leetcode-cn.com/problems/search-in-a-binary-search-tree)   |[44](https://leetcode-cn.com/problems/search-in-a-binary-search-tree/solution)|71.1%|简单|3.09%|
|1261|[在受污染的二叉树中查找元素](https://leetcode-cn.com/problems/find-elements-in-a-contaminated-binary-tree)   |[21](https://leetcode-cn.com/problems/find-elements-in-a-contaminated-binary-tree/solution)|69.2%|中等|&nbsp;|
|1145|[二叉树着色游戏](https://leetcode-cn.com/problems/binary-tree-coloring-game)   |[17](https://leetcode-cn.com/problems/binary-tree-coloring-game/solution)|37.2%|中等|&nbsp;|
|1110|[删点成林](https://leetcode-cn.com/problems/delete-nodes-and-return-forest)   |[24](https://leetcode-cn.com/problems/delete-nodes-and-return-forest/solution)|55.0%|中等|&nbsp;|
|1104|[二叉树寻路](https://leetcode-cn.com/problems/path-in-zigzag-labelled-binary-tree)   |[34](https://leetcode-cn.com/problems/path-in-zigzag-labelled-binary-tree/solution)|66.7%|中等|&nbsp;|
|1257|[最小公共区域](https://leetcode-cn.com/problems/smallest-common-region)   |[11](https://leetcode-cn.com/problems/smallest-common-region/solution)|46.6%|中等|&nbsp;|
|1028|[从先序遍历还原二叉树](https://leetcode-cn.com/problems/recover-a-tree-from-preorder-traversal)   |[16](https://leetcode-cn.com/problems/recover-a-tree-from-preorder-traversal/solution)|58.7%|困难|&nbsp;|
|1120|[子树的最大平均值](https://leetcode-cn.com/problems/maximum-average-subtree)   |[14](https://leetcode-cn.com/problems/maximum-average-subtree/solution)|55.9%|中等|&nbsp;|
|1022|[从根到叶的二进制数之和](https://leetcode-cn.com/problems/sum-of-root-to-leaf-binary-numbers)   |[29](https://leetcode-cn.com/problems/sum-of-root-to-leaf-binary-numbers/solution)|53.4%|简单|&nbsp;|
|998|[最大二叉树 II](https://leetcode-cn.com/problems/maximum-binary-tree-ii)   |[13](https://leetcode-cn.com/problems/maximum-binary-tree-ii/solution)|56.0%|中等|&nbsp;|
|987|[二叉树的垂序遍历](https://leetcode-cn.com/problems/vertical-order-traversal-of-a-binary-tree)   |[22](https://leetcode-cn.com/problems/vertical-order-traversal-of-a-binary-tree/solution)|36.8%|中等|&nbsp;|
|971|[翻转二叉树以匹配先序遍历](https://leetcode-cn.com/problems/flip-binary-tree-to-match-preorder-traversal)   |[10](https://leetcode-cn.com/problems/flip-binary-tree-to-match-preorder-traversal/solution)|41.4%|中等|&nbsp;|
|965|[单值二叉树](https://leetcode-cn.com/problems/univalued-binary-tree)   |[46](https://leetcode-cn.com/problems/univalued-binary-tree/solution)|66.1%|简单|&nbsp;|
|951|[翻转等价二叉树](https://leetcode-cn.com/problems/flip-equivalent-binary-trees)   |[13](https://leetcode-cn.com/problems/flip-equivalent-binary-trees/solution)|60.2%|中等|&nbsp;|
|919|[完全二叉树插入器](https://leetcode-cn.com/problems/complete-binary-tree-inserter)   |[16](https://leetcode-cn.com/problems/complete-binary-tree-inserter/solution)|58.8%|中等|&nbsp;|
|865|[具有所有最深结点的最小子树](https://leetcode-cn.com/problems/smallest-subtree-with-all-the-deepest-nodes)   |[11](https://leetcode-cn.com/problems/smallest-subtree-with-all-the-deepest-nodes/solution)|49.4%|中等|&nbsp;|
|431|[将 N 叉树编码为二叉树](https://leetcode-cn.com/problems/encode-n-ary-tree-to-binary-tree)   |[6](https://leetcode-cn.com/problems/encode-n-ary-tree-to-binary-tree/solution)|63.5%|困难|&nbsp;|
|742|[二叉树最近的叶节点](https://leetcode-cn.com/problems/closest-leaf-in-a-binary-tree)   |[14](https://leetcode-cn.com/problems/closest-leaf-in-a-binary-tree/solution)|44.0%|中等|&nbsp;|
|671|[二叉树中第二小的节点](https://leetcode-cn.com/problems/second-minimum-node-in-a-binary-tree)   |[42](https://leetcode-cn.com/problems/second-minimum-node-in-a-binary-tree/solution)|44.8%|简单|&nbsp;|
|666|[路径和 IV](https://leetcode-cn.com/problems/path-sum-iv)   |[15](https://leetcode-cn.com/problems/path-sum-iv/solution)|59.6%|中等|&nbsp;|
|655|[输出二叉树](https://leetcode-cn.com/problems/print-binary-tree)   |[18](https://leetcode-cn.com/problems/print-binary-tree/solution)|53.0%|中等|&nbsp;|
|623|[在二叉树中增加一行](https://leetcode-cn.com/problems/add-one-row-to-tree)   |[19](https://leetcode-cn.com/problems/add-one-row-to-tree/solution)|49.6%|中等|&nbsp;|
|549|[二叉树中最长的连续序列](https://leetcode-cn.com/problems/binary-tree-longest-consecutive-sequence-ii)   |[9](https://leetcode-cn.com/problems/binary-tree-longest-consecutive-sequence-ii/solution)|48.8%|中等|&nbsp;|
|510|[二叉搜索树中的中序后继 II](https://leetcode-cn.com/problems/inorder-successor-in-bst-ii)   |[8](https://leetcode-cn.com/problems/inorder-successor-in-bst-ii/solution)|54.7%|中等|&nbsp;|
|366|[寻找完全二叉树的叶子节点](https://leetcode-cn.com/problems/find-leaves-of-binary-tree)   |[15](https://leetcode-cn.com/problems/find-leaves-of-binary-tree/solution)|69.3%|中等|&nbsp;|
|285|[二叉搜索树中的顺序后继](https://leetcode-cn.com/problems/inorder-successor-in-bst)   |[18](https://leetcode-cn.com/problems/inorder-successor-in-bst/solution)|61.0%|中等|&nbsp;|
|272|[最接近的二叉搜索树值 II](https://leetcode-cn.com/problems/closest-binary-search-tree-value-ii)   |[13](https://leetcode-cn.com/problems/closest-binary-search-tree-value-ii/solution)|56.9%|困难|&nbsp;|
|250|[统计同值子树](https://leetcode-cn.com/problems/count-univalue-subtrees)   |[11](https://leetcode-cn.com/problems/count-univalue-subtrees/solution)|59.3%|中等|&nbsp;|
|156|[上下翻转二叉树](https://leetcode-cn.com/problems/binary-tree-upside-down)   |[13](https://leetcode-cn.com/problems/binary-tree-upside-down/solution)|73.5%|中等|&nbsp;|
