数学

两数相加

Add Two Numbers requires careful linked-list pointer manipulation to sum digits while handling carries efficiently in in…

整数反转

Reverse Integer challenges you to invert the digits of a signed 32-bit integer, handling overflow and negative values ca…

回文数

Determine if a given integer reads the same forward and backward using a math-driven solution strategy without convertin…

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.

两数相除

Solve Divide Two Integers by turning repeated subtraction into bit-shifted chunk subtraction with careful sign and overf…

字符串相乘

Multiply Strings requires simulating integer multiplication using only string operations without direct numeric conversi…

旋转图像

Rotate an n x n matrix 90 degrees clockwise in-place using array manipulation and mathematical indexing techniques effic…

Pow(x, n)

Calculate x to the power n efficiently using recursion and exponentiation, handling negative powers and large inputs saf…

排列序列

Find the kth permutation sequence of a set of numbers using math and recursion to efficiently compute the result.

不同路径

Calculate the number of unique paths for a robot to move on an m x n grid with only right and down movements.

加一

Given a number as an array of digits, increment it by one and return the updated array of digits.

二进制求和

Add Binary involves summing two binary strings and returning the result as a binary string using math and string manipul…

x 的平方根

Solve the Sqrt(x) problem using binary search to find the integer square root of a number without built-in operators.

爬楼梯

Climbing Stairs is a classic dynamic programming problem where you calculate distinct ways to reach the top using step t…

格雷编码

Generate an n-bit Gray Code sequence using backtracking with pruning and bit manipulation techniques.

不同的二叉搜索树

Given n nodes, calculate the number of unique binary search trees (BSTs) that can be formed with values from 1 to n.

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.

逆波兰表达式求值

Compute the result of an arithmetic expression in Reverse Polish Notation using a stack to manage operands efficiently.

分数到小数

Convert a fraction into a decimal, handling repeating decimals with parentheses around the repeating part.

Excel 表列名称

Convert a positive integer to its corresponding Excel column title using base-26 math and string manipulation efficientl…

Excel 表列序号

This problem requires converting an Excel column title into its corresponding column number by applying a math and strin…

阶乘后的零

Given a number n, find how many trailing zeroes are in n! using a math-driven approach.

轮转数组

Rotate Array challenges you to shift elements right by k steps using precise two-pointer scanning and invariant tracking…