哈希表

无重复字符的最长子串

Find the length of the longest substring without repeating characters using a sliding window and hash map to track state…

整数转罗马数字

Convert a given integer to its Roman numeral representation using hash table mapping and decimal place math operations e…

罗马数字转整数

Convert a Roman numeral string into an integer using a hash table and mathematical principles to determine value order.

电话号码的字母组合

Generate all letter combinations a digit string can represent using backtracking with pruning, leveraging hash table map…

串联所有单词的子串

Find all starting indices of substrings in a string that are concatenations of a given list of words.

有效的数独

Check if a 9x9 Sudoku board is valid by scanning rows, columns, and sub-boxes with hash lookups, ensuring no duplicates …

解数独

Solve the Sudoku puzzle by filling empty cells while respecting Sudoku's rules using array scanning and backtracking.

缺失的第一个正数

Identify the smallest missing positive integer in an unsorted array using constant space and linear time scanning techni…

字母异位词分组

Group the anagrams in a list of strings using efficient hash table-based methods, focusing on array scanning.

矩阵置零

Modify the matrix in place by setting rows and columns to zero when an element is zero.

最小覆盖子串

Find the smallest substring of s containing all characters from t using a sliding window with running state updates for …

从前序与中序遍历序列构造二叉树

Construct a binary tree using preorder and inorder traversal arrays, leveraging array scanning and hash table lookups.

从中序与后序遍历序列构造二叉树

Reconstruct a binary tree from given inorder and postorder arrays using array scanning and hash lookup to optimize recur…

单词接龙 II

Find all shortest transformation sequences from beginWord to endWord using a dictionary, leveraging backtracking search …

单词接龙

Find the shortest transformation sequence from a start word to an end word, with each word in the sequence differing by …

最长连续序列

Find the length of the longest consecutive elements sequence in an unsorted array using array scanning and hash lookup.

克隆图

Clone Graph involves cloning a graph using DFS, focusing on graph traversal and neighbor management using hash tables.

随机链表的复制

This problem requires copying a linked list where each node has a random pointer in addition to the next pointer.

单词拆分

Determine if a string can be fully segmented into dictionary words using array scanning and hash-based lookups for effic…

单词拆分 II

Given a string and dictionary, return all possible sentences by adding spaces where each word is in the dictionary.

环形链表

Determine if a given linked list contains a cycle using pointer manipulation or hashing, focusing on detecting repeated …

环形链表 II

Identify the start of a cycle in a linked list using pointer manipulation, efficiently handling edge cases without modif…

LRU 缓存

Implement an efficient LRU Cache using hash table and doubly-linked list to achieve O(1) operations for get and put.

直线上最多的点数

Find the maximum number of points on a straight line in a 2D plane using array scanning and hash lookup.