# 后端

|题目|出现次数|链接|
|-|-|-|
|215. 数组中的第K个最大元素|10|https://leetcode-cn.com/problems/kth-largest-element-in-an-array|
|92. 反转链表 II|7|https://leetcode-cn.com/problems/reverse-linked-list-ii|
|剑指 Offer 36. 二叉搜索树与双向链表|7|https://leetcode-cn.com/problems/er-cha-sou-suo-shu-yu-shuang-xiang-lian-biao-lcof|
|98. 验证二叉搜索树|7|https://leetcode-cn.com/problems/validate-binary-search-tree|
|148. 排序链表|7|https://leetcode-cn.com/problems/sort-list|
|200. 岛屿数量|6|https://leetcode-cn.com/problems/number-of-islands|
|328. 奇偶链表|6|https://leetcode-cn.com/problems/odd-even-linked-list|
|23. 合并K个排序链表|5|https://leetcode-cn.com/problems/merge-k-sorted-lists|
|306. 累加数|5|https://leetcode-cn.com/problems/additive-number|
|110. 平衡二叉树|5|https://leetcode-cn.com/problems/balanced-binary-tree|
|剑指 Offer 54. 二叉搜索树的第k大节点|5|https://leetcode-cn.com/problems/er-cha-sou-suo-shu-de-di-kda-jie-dian-lcof|
|56. 合并区间|5|https://leetcode-cn.com/problems/merge-intervals|
|33. 搜索旋转排序数组|5|https://leetcode-cn.com/problems/search-in-rotated-sorted-array|
|2. 两数相加|5|https://leetcode-cn.com/problems/add-two-numbers|
|146. LRU缓存机制|4|https://leetcode-cn.com/problems/lru-cache|
|94. 二叉树的中序遍历|4|https://leetcode-cn.com/problems/binary-tree-inorder-traversal|
|93. 复原IP地址|4|https://leetcode-cn.com/problems/restore-ip-addresses|
|113. 路径总和 II|4|https://leetcode-cn.com/problems/path-sum-ii|
|239. 滑动窗口最大值|4|https://leetcode-cn.com/problems/sliding-window-maximum|
|958. 二叉树的完全性检验|4|https://leetcode-cn.com/problems/check-completeness-of-a-binary-tree|
|543. 二叉树的直径|4|https://leetcode-cn.com/problems/diameter-of-binary-tree|
|25. K 个一组翻转链表|4|https://leetcode-cn.com/problems/reverse-nodes-in-k-group|
|104. 二叉树的最大深度|4|https://leetcode-cn.com/problems/maximum-depth-of-binary-tree|
|222. 完全二叉树的节点个数|3|https://leetcode-cn.com/problems/count-complete-tree-nodes|
|83. 删除排序链表中的重复元素|3|https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list|
|64. 最小路径和|3|https://leetcode-cn.com/problems/minimum-path-sum|
|695. 岛屿的最大面积|3|https://leetcode-cn.com/problems/max-area-of-island|
|剑指 Offer 27. 二叉树的镜像|3|https://leetcode-cn.com/problems/er-cha-shu-de-jing-xiang-lcof|
|74. 搜索二维矩阵|3|https://leetcode-cn.com/problems/search-a-2d-matrix|
|142. 环形链表 II|3|https://leetcode-cn.com/problems/linked-list-cycle-ii|
|369. 给单链表加一|3|https://leetcode-cn.com/problems/plus-one-linked-list|
|189. 旋转数组|3|https://leetcode-cn.com/problems/rotate-array|
|32. 最长有效括号|3|https://leetcode-cn.com/problems/longest-valid-parentheses|
|498. 对角线遍历|3|https://leetcode-cn.com/problems/diagonal-traverse|
|530. 二叉搜索树的最小绝对差|3|https://leetcode-cn.com/problems/minimum-absolute-difference-in-bst|
|814. 二叉树剪枝|2|https://leetcode-cn.com/problems/binary-tree-pruning|
|22. 括号生成|2|https://leetcode-cn.com/problems/generate-parentheses|
|1026. 节点与其祖先之间的最大差值|2|https://leetcode-cn.com/problems/maximum-difference-between-node-and-ancestor|
|199. 二叉树的右视图|2|https://leetcode-cn.com/problems/binary-tree-right-side-view|
|69. x 的平方根|2|https://leetcode-cn.com/problems/sqrtx|
|21. 合并两个有序链表|2|https://leetcode-cn.com/problems/merge-two-sorted-lists|
|86. 分隔链表|2|https://leetcode-cn.com/problems/partition-list|
|547. 省份数量（原朋友圈）|2|https://leetcode-cn.com/problems/number-of-provinces|
|662. 二叉树最大宽度|2|https://leetcode-cn.com/problems/maximum-width-of-binary-tree|
|34. 在排序数组中查找元素的第一个和最后一个位置|2|https://leetcode-cn.com/problems/find-first-and-last-position-of-element-in-sorted-array|
|674. 最长连续递增序列|2|https://leetcode-cn.com/problems/longest-continuous-increasing-subsequence|
|101. 对称二叉树|2|https://leetcode-cn.com/problems/symmetric-tree|
|986. 区间列表的交集|2|https://leetcode-cn.com/problems/interval-list-intersections|
|剑指 Offer 22. 链表中倒数第k个节点|2|https://leetcode-cn.com/problems/lian-biao-zhong-dao-shu-di-kge-jie-dian-lcof|
|54. 螺旋矩阵|2|https://leetcode-cn.com/problems/spiral-matrix|
|143. 重排链表|2|https://leetcode-cn.com/problems/reorder-list|
|7. 整数反转|2|https://leetcode-cn.com/problems/reverse-integer|
|386. 字典序排数|2|https://leetcode-cn.com/problems/lexicographical-numbers|
|82. 删除排序链表中的重复元素 II|2|https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list-ii|
|232. 用栈实现队列|2|https://leetcode-cn.com/problems/implement-queue-using-stacks|
|1038. 从二叉搜索树到更大和树|2|https://leetcode-cn.com/problems/binary-search-tree-to-greater-sum-tree|
|206. 反转链表|2|https://leetcode-cn.com/problems/reverse-linked-list|
|400. 第N个数字|2|https://leetcode-cn.com/problems/nth-digit|
|221. 最大正方形|2|https://leetcode-cn.com/problems/maximal-square|
|1. 两数之和|2|https://leetcode-cn.com/problems/two-sum|
|5. 最长回文子串|2|https://leetcode-cn.com/problems/longest-palindromic-substring|
|402. 移掉K位数字|2|https://leetcode-cn.com/problems/remove-k-digits|
|52. N皇后 II|1|https://leetcode-cn.com/problems/n-queens-ii|
|103. 二叉树的锯齿形层次遍历|1|https://leetcode-cn.com/problems/binary-tree-zigzag-level-order-traversal|
|8. 字符串转换整数 (atoi)|1|https://leetcode-cn.com/problems/string-to-integer-atoi|
|145. 二叉树的后序遍历|1|https://leetcode-cn.com/problems/binary-tree-postorder-traversal|
|41. 缺失的第一个正数|1|https://leetcode-cn.com/problems/first-missing-positive|
|剑指 Offer 45. 把数组排成最小的数|1|https://leetcode-cn.com/problems/ba-shu-zu-pai-cheng-zui-xiao-de-shu-lcof|
|226. 翻转二叉树|1|https://leetcode-cn.com/problems/invert-binary-tree|
|补充题12. 二叉树的下一个节点|1||
|394. 字符串解码|1|https://leetcode-cn.com/problems/decode-string|
|24. 两两交换链表中的节点|1|https://leetcode-cn.com/problems/swap-nodes-in-pairs|
|141. 环形链表|1|https://leetcode-cn.com/problems/linked-list-cycle|
|442. 数组中重复的数据|1|https://leetcode-cn.com/problems/find-all-duplicates-in-an-array|
|补充题4. 手撕快速排序|1||
|14. 最长公共前缀|1|https://leetcode-cn.com/problems/longest-common-prefix|
|297. 二叉树的序列化与反序列化|1|https://leetcode-cn.com/problems/serialize-and-deserialize-binary-tree|
|242. 有效的字母异位词|1|https://leetcode-cn.com/problems/valid-anagram|
|235. 二叉搜索树的最近公共祖先|1|https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-search-tree|
|240. 搜索二维矩阵 II|1|https://leetcode-cn.com/problems/search-a-2d-matrix-ii|
|349. 两个数组的交集|1|https://leetcode-cn.com/problems/intersection-of-two-arrays|
|562. 矩阵中最长的连续1线段|1|https://leetcode-cn.com/problems/longest-line-of-consecutive-one-in-matrix|
|305. 岛屿数量 II|1|https://leetcode-cn.com/problems/number-of-islands-ii|
|99. 恢复二叉搜索树|1|https://leetcode-cn.com/problems/recover-binary-search-tree|
|108. 将有序数组转换为二叉搜索树|1|https://leetcode-cn.com/problems/convert-sorted-array-to-binary-search-tree|
|560. 和为K的子数组|1|https://leetcode-cn.com/problems/subarray-sum-equals-k|
|62. 不同路径|1|https://leetcode-cn.com/problems/unique-paths|
|26. 删除排序数组中的重复项|1|https://leetcode-cn.com/problems/remove-duplicates-from-sorted-array|
|435. 无重叠区间|1|https://leetcode-cn.com/problems/non-overlapping-intervals|
|136. 只出现一次的数字|1|https://leetcode-cn.com/problems/single-number|
|889. 根据前序和后序遍历构造二叉树|1|https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-postorder-traversal|
|剑指 Offer 09. 用两个栈实现队列|1|https://leetcode-cn.com/problems/yong-liang-ge-zhan-shi-xian-dui-lie-lcof|
|236. 二叉树的最近公共祖先|1|https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-tree|
|329. 矩阵中的最长递增路径|1|https://leetcode-cn.com/problems/longest-increasing-path-in-a-matrix|
|102. 二叉树的层序遍历|1|https://leetcode-cn.com/problems/binary-tree-level-order-traversal|
|316. 去除重复字母|1|https://leetcode-cn.com/problems/remove-duplicate-letters|
|312. 戳气球|1|https://leetcode-cn.com/problems/burst-balloons|
|208. 实现 Trie (前缀树)|1|https://leetcode-cn.com/problems/implement-trie-prefix-tree|
|405. 数字转换为十六进制数|1|https://leetcode-cn.com/problems/convert-a-number-to-hexadecimal|
|704. 二分查找|1|https://leetcode-cn.com/problems/binary-search|
|20. 有效的括号|1|https://leetcode-cn.com/problems/valid-parentheses|
|516. 最长回文子序列|1|https://leetcode-cn.com/problems/longest-palindromic-subsequence|
|151. 翻转字符串里的单词|1|https://leetcode-cn.com/problems/reverse-words-in-a-string|
|416. 分割等和子集|1|https://leetcode-cn.com/problems/partition-equal-subset-sum|
|572. 另一个树的子树|1|https://leetcode-cn.com/problems/subtree-of-another-tree|
|450. 删除二叉搜索树中的节点|1|https://leetcode-cn.com/problems/delete-node-in-a-bst|
|48. 旋转图像|1|https://leetcode-cn.com/problems/rotate-image|
|剑指 Offer 25. 合并两个排序的链表|1|https://leetcode-cn.com/problems/he-bing-liang-ge-pai-xu-de-lian-biao-lcof|
|4. 寻找两个正序数组的中位数|1|https://leetcode-cn.com/problems/median-of-two-sorted-arrays|
|剑指 Offer 24. 反转链表|1|https://leetcode-cn.com/problems/fan-zhuan-lian-biao-lcof|
|556. 下一个更大元素 III|1|https://leetcode-cn.com/problems/next-greater-element-iii|
|658. 找到 K 个最接近的元素|1|https://leetcode-cn.com/problems/find-k-closest-elements|
|剑指 Offer 11. 旋转数组的最小数字|1|https://leetcode-cn.com/problems/xuan-zhuan-shu-zu-de-zui-xiao-shu-zi-lcof|
|17. 电话号码的字母组合|1|https://leetcode-cn.com/problems/letter-combinations-of-a-phone-number|
|168. Excel表列名称|1|https://leetcode-cn.com/problems/excel-sheet-column-title|
|43. 字符串相乘|1|https://leetcode-cn.com/problems/multiply-strings|
|31. 下一个排列|1|https://leetcode-cn.com/problems/next-permutation|
|105. 从前序与中序遍历序列构造二叉树|1|https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal|
|468. 验证IP地址|1|https://leetcode-cn.com/problems/validate-ip-address|
|109. 有序链表转换二叉搜索树|1|https://leetcode-cn.com/problems/convert-sorted-list-to-binary-search-tree|
|71. 简化路径|1|https://leetcode-cn.com/problems/simplify-path|
|124. 二叉树中的最大路径和|1|https://leetcode-cn.com/problems/binary-tree-maximum-path-sum|
|79. 单词搜索|1|https://leetcode-cn.com/problems/word-search|
|剑指 Offer 32 - I. 从上到下打印二叉树|1|https://leetcode-cn.com/problems/cong-shang-dao-xia-da-yin-er-cha-shu-lcof|
|60. 第k个排列|1|https://leetcode-cn.com/problems/permutation-sequence|
|130. 被围绕的区域|1|https://leetcode-cn.com/problems/surrounded-regions|
|40. 组合总和 II|1|https://leetcode-cn.com/problems/combination-sum-ii|
|59. 螺旋矩阵 II|1|https://leetcode-cn.com/problems/spiral-matrix-ii|
|225. 用队列实现栈|1|https://leetcode-cn.com/problems/implement-stack-using-queues|
|47. 全排列 II|1|https://leetcode-cn.com/problems/permutations-ii|
|343. 整数拆分|1|https://leetcode-cn.com/problems/integer-break|
|448. 找到所有数组中消失的数字|1|https://leetcode-cn.com/problems/find-all-numbers-disappeared-in-an-array|
|152. 乘积最大子数组|1|https://leetcode-cn.com/problems/maximum-product-subarray|
|259. 较小的三数之和|1|https://leetcode-cn.com/problems/3sum-smaller|
|415. 字符串相加|1|https://leetcode-cn.com/problems/add-strings|
|257. 二叉树的所有路径|1|https://leetcode-cn.com/problems/binary-tree-paths|
|540. 有序数组中的单一元素|1|https://leetcode-cn.com/problems/single-element-in-a-sorted-array|
|1325. 删除给定值的叶子节点|1|https://leetcode-cn.com/problems/delete-leaves-with-a-given-value|
|160. 相交链表|1|https://leetcode-cn.com/problems/intersection-of-two-linked-lists|
|42. 接雨水|1|https://leetcode-cn.com/problems/trapping-rain-water|
|剑指 Offer 12. 矩阵中的路径|1|https://leetcode-cn.com/problems/ju-zhen-zhong-de-lu-jing-lcof|