数据研发 我开发的CodeTop题库可以按照部门、难度筛选，比markdown更方便查询高频题 题目 出现次数 链接 232. 用栈实现队列 4 https://leetcode-cn.com/problems/implement-queue-using-stacks 146. LRU缓存机制 3 https://leetcode-cn.com/problems/lru-cache 121. 买卖股票的最佳时机 3 https://leetcode-cn.com/problems/best-time-to-buy-and-sell-stock 101. 对称二叉树 3 https://leetcode-cn.com/problems/symmetric-tree 25. K 个一组翻转链表 3 https://leetcode-cn.com/problems/reverse-nodes-in-k-group 98. 验证二叉搜索树 2 https://leetcode-cn.com/problems/validate-binary-search-tree 103. 二叉树的锯齿形层次遍历 2 https://leetcode-cn.com/problems/binary-tree-zigzag-level-order-traversal 141. 环形链表 2 https://leetcode-cn.com/problems/linked-list-cycle 53. 最大子序和 2 https://leetcode-cn.com/problems/maximum-subarray 64. 最小路径和 2 https://leetcode-cn.com/problems/minimum-path-sum 200. 岛屿数量 2 https://leetcode-cn.com/problems/number-of-islands 补充题1. 排序奇升偶降链表 2 https://mp.weixin.qq.com/s/0WVa2wIAeG0nYnVndZiEXQ 94. 二叉树的中序遍历 1 https://leetcode-cn.com/problems/binary-tree-inorder-traversal 补充题6. 手撕堆排序 1 https://leetcode-cn.com/problems/sort-an-array 剑指 Offer 53 - I. 在排序数组中查找数字 I 1 https://leetcode-cn.com/problems/zai-pai-xu-shu-zu-zhong-cha-zhao-shu-zi-lcof 122. 买卖股票的最佳时机 II 1 https://leetcode-cn.com/problems/best-time-to-buy-and-sell-stock-ii 230. 二叉搜索树中第K小的元素 1 https://leetcode-cn.com/problems/kth-smallest-element-in-a-bst 142. 环形链表 II 1 https://leetcode-cn.com/problems/linked-list-cycle-ii 69. x 的平方根 1 https://leetcode-cn.com/problems/sqrtx 611. 有效三角形的个数 1 https://leetcode-cn.com/problems/valid-triangle-number 221. 最大正方形 1 https://leetcode-cn.com/problems/maximal-square 剑指 Offer 51. 数组中的逆序对 1 https://leetcode-cn.com/problems/shu-zu-zhong-de-ni-xu-dui-lcof 43. 字符串相乘 1 https://leetcode-cn.com/problems/multiply-strings 补充题14. 阿拉伯数字转中文数字 1 16. 最接近的三数之和 1 https://leetcode-cn.com/problems/3sum-closest 102. 二叉树的层序遍历 1 https://leetcode-cn.com/problems/binary-tree-level-order-traversal 215. 数组中的第K个最大元素 1 https://leetcode-cn.com/problems/kth-largest-element-in-an-array 1201. 丑数 III 1 https://leetcode-cn.com/problems/ugly-number-iii 240. 搜索二维矩阵 II 1 https://leetcode-cn.com/problems/search-a-2d-matrix-ii 剑指 Offer 41. 数据流中的中位数 1 https://leetcode-cn.com/problems/shu-ju-liu-zhong-de-zhong-wei-shu-lcof 112. 路径总和 1 https://leetcode-cn.com/problems/path-sum 3. 无重复字符的最长子串 1 https://leetcode-cn.com/problems/longest-substring-without-repeating-characters 剑指 Offer 59 - II. 队列的最大值 1 https://leetcode-cn.com/problems/dui-lie-de-zui-da-zhi-lcof 297. 二叉树的序列化与反序列化 1 https://leetcode-cn.com/problems/serialize-and-deserialize-binary-tree 92. 反转链表 II 1 https://leetcode-cn.com/problems/reverse-linked-list-ii 226. 翻转二叉树 1 https://leetcode-cn.com/problems/invert-binary-tree 440. 字典序的第K小数字 1 https://leetcode-cn.com/problems/k-th-smallest-in-lexicographical-order 206. 反转链表 1 https://leetcode-cn.com/problems/reverse-linked-list 42. 接雨水 1 https://leetcode-cn.com/problems/trapping-rain-water 704. 二分查找 1 https://leetcode-cn.com/problems/binary-search 60. 第k个排列 1 https://leetcode-cn.com/problems/permutation-sequence 516. 最长回文子序列 1 https://leetcode-cn.com/problems/longest-palindromic-subsequence 718. 最长重复子数组 1 https://leetcode-cn.com/problems/maximum-length-of-repeated-subarray 5. 最长回文子串 1 https://leetcode-cn.com/problems/longest-palindromic-substring 155. 最小栈 1 https://leetcode-cn.com/problems/min-stack 33. 搜索旋转排序数组 1 https://leetcode-cn.com/problems/search-in-rotated-sorted-array 113. 路径总和 II 1 https://leetcode-cn.com/problems/path-sum-ii 143. 重排链表 1 https://leetcode-cn.com/problems/reorder-list 148. 排序链表 1 https://leetcode-cn.com/problems/sort-list 138. 复制带随机指针的链表 1 https://leetcode-cn.com/problems/copy-list-with-random-pointer