数组·哈希·扫描模式

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.

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…

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.

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.

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.

多数元素

Find the majority element in an array, where the element appears more than n/2 times, using efficient algorithms.

存在重复元素

Determine if an integer array contains any duplicate values by efficiently scanning with a hash lookup to ensure fast de…

存在重复元素 II

Check if any two equal numbers exist within k indices using array scanning and hash table lookup efficiently.

多数元素 II

Identify all elements in an integer array appearing more than ⌊ n/3 ⌋ times using efficient array scanning and hash coun…

丢失的数字

Find the missing number in an array containing distinct numbers in the range [0, n].

回文对

Find all pairs of words in a list that form palindromes when concatenated using efficient scanning and hash mapping.

前 K 个高频元素

Find the k most frequent elements from an array using efficient algorithms like hashing and sorting.

两个数组的交集

Find the intersection of two arrays while ensuring unique elements using efficient array scanning and hash lookups.

两个数组的交集 II

Find the intersection of two arrays, accounting for multiple occurrences of the same number.

O(1) 时间插入、删除和获取随机元素

Implement a data structure supporting insert, delete, and getRandom in average O(1) using array plus hash mapping.

O(1) 时间插入、删除和获取随机元素 - 允许重复

This problem challenges you to design a data structure that supports insertion, removal, and random access with O(1) tim…

完美矩形

Determine if given axis-aligned rectangles form a perfect cover using array scanning and hash-based corner counting tech…

数组中两个数的最大异或值

Find the maximum XOR of two numbers in an integer array using efficient bit manipulation techniques.