algorithm

A Python matrix simulation using direction vectors and in-place visit markers

An O(n²) Python DP solution that tracks the longest increasing subsequence ending at each index

A WordDictionary implementation using a Trie for storage and DFS for wildcard search

A Python two-pointer solution that moves the height limiting the current area

A Python stack solution that validates bracket type and closing order

Implementing a Trie with fixed 26-child nodes and an is_end marker

A Python dynamic programming solution for checking whether a string can be segmented by a word dictionary

Encoding and restoring a list of strings by recording each string's length and a delimiter

Grouping anagram strings by using each sorted string as the hash map key

A one-pass Python solution that tracks the lowest earlier price to calculate maximum profit

A Python DFS and memoization solution that stores the minimum coin count for each remaining amount

A Python DFS and backtracking solution that marks visited board cells in place

A Python binary search solution for the minimum value in a rotated sorted array

A Python DFS solution that compares the depths of the left and right subtrees

A Python solution that merges two sorted linked lists with a dummy node and moving pointers

A Python recursion and memoization solution that counts valid one-digit and two-digit decodings

A Python solution using Kadane's algorithm to find the maximum sum of a contiguous subarray

A Python backtracking solution to Combination Sum using a start index and pruning

A Python solution that counts 1 bits by repeatedly dividing by 2

A two-pointer Python solution for checking palindromes after normalizing alphanumeric characters

A DFS Python solution for checking whether a BST is built with valid value ranges

A 3Sum solution using sorting and a two-sum-style hash map approach.

A left-product and right-product solution for Product of Array Except Self.

A recursion and memoization write-up for the Climbing Stairs problem.

A comparison of sorting and character counting for the Valid Anagram problem.

Solving the rob-or-skip choice with top-down DP and memoization

Using a set to count each consecutive sequence only from its starting point

Using frequency counting and bucket arrays to return the top k frequent elements

Comparing brute force, two-pass hash map, and one-pass hash map approaches for Two Sum

Comparing brute force, sorting, and hash set approaches for duplicate detection

Solving BST range sum through BFS, DFS, and prefix sums

Why a modified Bellman-Ford approach fits the K-stop constraint better, and some implementation notes