string

Longest Substring Without Repeating Characters

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

Longest Palindromic Substring

Find the longest contiguous palindromic substring in a given string using dynamic programming and two-pointer expansion …

Zigzag Conversion

Convert a string into a zigzag pattern across multiple rows and read it line by line efficiently for string manipulation…

String to Integer (atoi)

Convert a string to a 32-bit signed integer by carefully parsing characters, handling signs, and ignoring invalid traili…

Regular Expression Matching

The Regular Expression Matching problem involves checking if a string matches a pattern using '.' and '*'.

Integer to Roman

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

Roman to Integer

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

Longest Common Prefix

Find the longest common prefix in an array of strings, returning an empty string if none exists.

Letter Combinations of a Phone Number

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

Valid Parentheses

Determine if a string of parentheses, brackets, and braces is correctly nested using a stack for proper order validation…

Generate Parentheses

Generate Parentheses requires generating all valid combinations of parentheses with given pairs using backtracking and s…

Find the Index of the First Occurrence in a String

Locate the first occurrence of a substring within a string using a two-pointer scanning strategy and invariant tracking …

Substring with Concatenation of All Words

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

Longest Valid Parentheses

Compute the length of the longest well-formed parentheses substring using state transition dynamic programming and stack…

Count and Say

Count and Say requires building the nth sequence term by iteratively applying a run-length encoding on strings of digits…

Multiply Strings

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

Wildcard Matching

Implement full wildcard pattern matching using '?' and '*' by applying state transition dynamic programming with careful…

Group Anagrams

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

Length of Last Word

Determine the length of the last word in a string using a focused string-driven approach to handle spaces and trailing c…

Valid Number

Determine if a given string represents a valid number using precise string parsing and character validation rules.

Add Binary

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

Text Justification

Text Justification requires packing words into lines to match a specified width, ensuring even distribution of spaces.

Simplify Path

Simplify a Unix-style path by transforming it into its canonical form using stack-based state management.

Edit Distance

Determine the minimum number of insertions, deletions, or replacements to transform one string into another using dynami…