Pro only = 需要 SSO
LC 1 · Two SumEasy · array, hash-table · primary: 前缀状态 + 哈希频次
LC 1–100
FreeLC 1–100
LC 2 · Add Two NumbersMedium · linked-list, math, recursion · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 3 · Longest Substring Without Repeating CharactersMedium · hash-table, sliding-window, string · primary: 可变长滑动窗口
LC 1–100
FreeLC 1–100
LC 4 · Median of Two Sorted ArraysHard · array, binary-search, divide-and-conquer · primary: 有序域二分查找
LC 1–100
FreeLC 1–100
LC 5 · Longest Palindromic SubstringMedium · dynamic-programming, string, two-pointers · primary: 中心扩展 / Manacher 回文
LC 1–100
FreeLC 1–100
LC 6 · Zigzag ConversionMedium · string · primary: 字符串解析 / Token 状态机
LC 1–100
FreeLC 1–100
LC 7 · Reverse IntegerMedium · math · primary: 模运算与快速幂
LC 1–100
FreeLC 1–100
LC 8 · String to Integer (atoi)Medium · string · primary: 字符串解析 / Token 状态机
LC 1–100
FreeLC 1–100
LC 9 · Palindrome NumberEasy · math · primary: 相向双指针
LC 1–100
FreeLC 1–100
LC 10 · Regular Expression MatchingHard · dynamic-programming, recursion, string · primary: 线性 DP / 一维状态递推
LC 1–100
FreeLC 1–100
LC 11 · Container With Most WaterMedium · array, greedy, two-pointers · primary: 相向双指针
LC 1–100
FreeLC 1–100
LC 12 · Integer to RomanMedium · hash-table, math, string · primary: 前缀状态 + 哈希频次
LC 1–100
FreeLC 1–100
LC 13 · Roman to IntegerEasy · hash-table, math, string · primary: 前缀状态 + 哈希频次
LC 1–100
FreeLC 1–100
LC 14 · Longest Common PrefixEasy · array, string, trie · primary: Trie 前缀树
LC 1–100
FreeLC 1–100
LC 15 · 3SumMedium · array, sorting, two-pointers · primary: 相向双指针
LC 1–100
FreeLC 1–100
LC 16 · 3Sum ClosestMedium · array, sorting, two-pointers · primary: 相向双指针
LC 1–100
FreeLC 1–100
LC 17 · Letter Combinations of a Phone NumberMedium · backtracking, hash-table, string · primary: 子集 / 组合回溯
LC 1–100
FreeLC 1–100
LC 18 · 4SumMedium · array, sorting, two-pointers · primary: 相向双指针
LC 1–100
FreeLC 1–100
LC 19 · Remove Nth Node From End of ListMedium · linked-list, two-pointers · primary: 同向双指针 / 读写指针
LC 1–100
FreeLC 1–100
LC 20 · Valid ParenthesesEasy · stack, string · primary: 括号匹配栈
LC 1–100
FreeLC 1–100
LC 21 · Merge Two Sorted ListsEasy · linked-list, recursion · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 22 · Generate ParenthesesMedium · backtracking, dynamic-programming, string · primary: 括号匹配栈
LC 1–100
FreeLC 1–100
LC 23 · Merge k Sorted ListsHard · divide-and-conquer, heap-priority-queue, linked-list, merge-sort · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 24 · Swap Nodes in PairsMedium · linked-list, recursion · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 25 · Reverse Nodes in k-GroupHard · linked-list, recursion · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 26 · Remove Duplicates from Sorted ArrayEasy · array, two-pointers · primary: 同向双指针 / 读写指针
LC 1–100
FreeLC 1–100
LC 27 · Remove ElementEasy · array, two-pointers · primary: 同向双指针 / 读写指针
LC 1–100
FreeLC 1–100
LC 28 · Find the Index of the First Occurrence in a StringEasy · string, string-matching, two-pointers · primary: KMP / 前缀函数字符串匹配
LC 1–100
FreeLC 1–100
LC 29 · Divide Two IntegersMedium · bit-manipulation, math · primary: 位运算不变量 / XOR 消去
LC 1–100
FreeLC 1–100
LC 30 · Substring with Concatenation of All WordsHard · hash-table, sliding-window, string · primary: 可变长滑动窗口
LC 1–100
FreeLC 1–100
LC 31 · Next PermutationMedium · array, two-pointers · primary: 排列回溯
LC 1–100
FreeLC 1–100
LC 32 · Longest Valid ParenthesesHard · dynamic-programming, stack, string · primary: 括号匹配栈
LC 1–100
FreeLC 1–100
LC 33 · Search in Rotated Sorted ArrayMedium · array, binary-search · primary: 有序域二分查找
LC 1–100
FreeLC 1–100
FreeLC 1–100
LC 35 · Search Insert PositionEasy · array, binary-search · primary: 二分边界 / First True
LC 1–100
FreeLC 1–100
LC 36 · Valid SudokuMedium · array, hash-table, matrix · primary: 约束满足回溯
LC 1–100
FreeLC 1–100
LC 37 · Sudoku SolverHard · array, backtracking, hash-table, matrix · primary: 约束满足回溯
LC 1–100
FreeLC 1–100
LC 38 · Count and SayMedium · string · primary: 字符串解析 / Token 状态机
LC 1–100
FreeLC 1–100
LC 39 · Combination SumMedium · array, backtracking · primary: 子集 / 组合回溯
LC 1–100
FreeLC 1–100
LC 40 · Combination Sum IIMedium · array, backtracking · primary: 子集 / 组合回溯
LC 1–100
FreeLC 1–100
LC 41 · First Missing PositiveHard · array, hash-table · primary: 二分边界 / First True
LC 1–100
FreeLC 1–100
LC 42 · Trapping Rain WaterHard · array, dynamic-programming, monotonic-stack, stack, two-pointers · primary: 单调栈找最近更大/更小
LC 1–100
FreeLC 1–100
LC 43 · Multiply StringsMedium · math, simulation, string · primary: 显式模拟 / 状态机
LC 1–100
FreeLC 1–100
LC 44 · Wildcard MatchingHard · dynamic-programming, greedy, recursion, string · primary: 线性 DP / 一维状态递推
LC 1–100
FreeLC 1–100
LC 45 · Jump Game IIMedium · array, dynamic-programming, greedy · primary: 交换论证 / 局部最优排序
LC 1–100
FreeLC 1–100
LC 46 · PermutationsMedium · array, backtracking · primary: 排列回溯
LC 1–100
FreeLC 1–100
LC 47 · Permutations IIMedium · array, backtracking, sorting · primary: 排列回溯
LC 1–100
FreeLC 1–100
LC 48 · Rotate ImageMedium · array, math, matrix · primary: 网格 Flood Fill
LC 1–100 + 首个 family 候选相关
FreeLC 1–100 + 首个 family 候选相关
LC 49 · Group AnagramsMedium · array, hash-table, sorting, string · primary: 频次表 / 坐标计数
LC 1–100
FreeLC 1–100
LC 50 · Pow(x, n)Medium · math, recursion · primary: 模运算与快速幂
LC 1–100
FreeLC 1–100
LC 51 · N-QueensHard · array, backtracking · primary: 约束满足回溯
LC 1–100
FreeLC 1–100
LC 52 · N-Queens IIHard · backtracking · primary: 约束满足回溯
LC 1–100
FreeLC 1–100
LC 53 · Maximum SubarrayMedium · array, divide-and-conquer, dynamic-programming · primary: 分治：拆分、递归、合并
LC 1–100
FreeLC 1–100
LC 54 · Spiral MatrixMedium · array, matrix, simulation · primary: 显式模拟 / 状态机
LC 1–100
FreeLC 1–100
LC 55 · Jump GameMedium · array, dynamic-programming, greedy · primary: 交换论证 / 局部最优排序
LC 1–100
FreeLC 1–100
LC 56 · Merge IntervalsMedium · array, sorting · primary: 区间排序贪心
LC 1–100
FreeLC 1–100
LC 57 · Insert IntervalMedium · array · primary: 区间排序贪心
LC 1–100
FreeLC 1–100
LC 58 · Length of Last WordEasy · string · primary: 二分边界 / First True
LC 1–100
FreeLC 1–100
LC 59 · Spiral Matrix IIMedium · array, matrix, simulation · primary: 显式模拟 / 状态机
LC 1–100
FreeLC 1–100
LC 60 · Permutation SequenceHard · math, recursion · primary: 排列回溯
LC 1–100
FreeLC 1–100
LC 61 · Rotate ListMedium · linked-list, two-pointers · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 62 · Unique PathsMedium · combinatorics, dynamic-programming, math · primary: 网格 DP
LC 1–100
FreeLC 1–100
LC 63 · Unique Paths IIMedium · array, dynamic-programming, matrix · primary: 网格 DP
LC 1–100
FreeLC 1–100
LC 64 · Minimum Path SumMedium · array, dynamic-programming, matrix · primary: 网格 DP
LC 1–100
FreeLC 1–100
LC 65 · Valid NumberHard · string · primary: 字符串解析 / Token 状态机
LC 1–100
FreeLC 1–100
LC 66 · Plus OneEasy · array, math · primary: 模运算与快速幂
LC 1–100
FreeLC 1–100
LC 67 · Add BinaryEasy · bit-manipulation, math, simulation, string · primary: 显式模拟 / 状态机
LC 1–100
FreeLC 1–100
LC 68 · Text JustificationHard · array, simulation, string · primary: 显式模拟 / 状态机
LC 1–100
FreeLC 1–100
LC 69 · Sqrt(x)Easy · binary-search, math · primary: 有序域二分查找
LC 1–100
FreeLC 1–100
LC 70 · Climbing StairsEasy · dynamic-programming, math, memoization · primary: 线性 DP / 一维状态递推
LC 1–100
FreeLC 1–100
LC 71 · Simplify PathMedium · stack, string · primary: 栈式状态模拟
LC 1–100
FreeLC 1–100
LC 72 · Edit DistanceMedium · dynamic-programming, string · primary: 子序列 DP
LC 1–100
FreeLC 1–100
LC 73 · Set Matrix ZeroesMedium · array, hash-table, matrix · primary: 前缀状态 + 哈希频次
LC 1–100
FreeLC 1–100
LC 74 · Search a 2D MatrixMedium · array, binary-search, matrix · primary: 有序域二分查找
LC 1–100
FreeLC 1–100
LC 75 · Sort ColorsMedium · array, sorting, two-pointers · primary: 相向双指针
LC 1–100
FreeLC 1–100
LC 76 · Minimum Window SubstringHard · hash-table, sliding-window, string · primary: 可变长滑动窗口
LC 1–100
FreeLC 1–100
LC 77 · CombinationsMedium · backtracking · primary: 子集 / 组合回溯
LC 1–100
FreeLC 1–100
LC 78 · SubsetsMedium · array, backtracking, bit-manipulation · primary: 子集 / 组合回溯
LC 1–100
FreeLC 1–100
LC 79 · Word SearchMedium · array, backtracking, depth-first-search, matrix, string · primary: 约束满足回溯
LC 1–100 + 首个 family 候选相关
FreeLC 1–100 + 首个 family 候选相关
LC 80 · Remove Duplicates from Sorted Array IIMedium · array, two-pointers · primary: 同向双指针 / 读写指针
LC 1–100
FreeLC 1–100
LC 81 · Search in Rotated Sorted Array IIMedium · array, binary-search · primary: 有序域二分查找
LC 1–100
FreeLC 1–100
LC 82 · Remove Duplicates from Sorted List IIMedium · linked-list, two-pointers · primary: 同向双指针 / 读写指针
LC 1–100
FreeLC 1–100
LC 83 · Remove Duplicates from Sorted ListEasy · linked-list · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 84 · Largest Rectangle in HistogramHard · array, monotonic-stack, stack · primary: 单调栈找最近更大/更小
LC 1–100
FreeLC 1–100
LC 85 · Maximal RectangleHard · array, dynamic-programming, matrix, monotonic-stack, stack · primary: 网格 DP
LC 1–100
FreeLC 1–100
LC 86 · Partition ListMedium · linked-list, two-pointers · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 87 · Scramble StringHard · dynamic-programming, string · primary: 线性 DP / 一维状态递推
LC 1–100
FreeLC 1–100
LC 88 · Merge Sorted ArrayEasy · array, sorting, two-pointers · primary: 同向双指针 / 读写指针
LC 1–100
FreeLC 1–100
LC 89 · Gray CodeMedium · backtracking, bit-manipulation, math · primary: 约束满足回溯
LC 1–100
FreeLC 1–100
LC 90 · Subsets IIMedium · array, backtracking, bit-manipulation · primary: 子集 / 组合回溯
LC 1–100
FreeLC 1–100
LC 91 · Decode WaysMedium · dynamic-programming, string · primary: 线性 DP / 一维状态递推
LC 1–100
FreeLC 1–100
LC 92 · Reverse Linked List IIMedium · linked-list · primary: 链表指针改线
LC 1–100
FreeLC 1–100
LC 93 · Restore IP AddressesMedium · backtracking, string · primary: 约束满足回溯
LC 1–100
FreeLC 1–100
LC 94 · Binary Tree Inorder TraversalEasy · binary-tree, depth-first-search, stack, tree · primary: 树递归聚合 / 后序返回值
LC 1–100 + 首个 family 候选相关
FreeLC 1–100 + 首个 family 候选相关
LC 95 · Unique Binary Search Trees IIMedium · backtracking, binary-search-tree, binary-tree, dynamic-programming, tree · primary: 树形 DP
LC 1–100
FreeLC 1–100
LC 96 · Unique Binary Search TreesMedium · binary-search-tree, binary-tree, dynamic-programming, math, tree · primary: 树形 DP
LC 1–100
FreeLC 1–100
LC 97 · Interleaving StringMedium · dynamic-programming, string · primary: 线性 DP / 一维状态递推
LC 1–100
FreeLC 1–100
LC 98 · Validate Binary Search TreeMedium · binary-search-tree, binary-tree, depth-first-search, tree · primary: BST 有序性 / 中序遍历
LC 1–100
FreeLC 1–100
LC 99 · Recover Binary Search TreeMedium · binary-search-tree, binary-tree, depth-first-search, tree · primary: BST 有序性 / 中序遍历
LC 1–100
FreeLC 1–100
LC 100 · Same TreeEasy · binary-tree, breadth-first-search, depth-first-search, tree · primary: 树的层序 BFS
LC 1–100 + 首个 family 候选相关
FreeLC 1–100 + 首个 family 候选相关