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Find the lowest common ancestor (LCA) of two given nodes in a binary search tree, where the LCA is the deepest node that has both nodes as descendants.

Watch pointers move through a linked list reversal line by line. Interactive visualization with TraceLit.

Given an array of stone weights, repeatedly smash the two heaviest stones together until at most one stone remains, returning the weight of the last stone or 0

Determine if it''s possible to finish all courses given a list of prerequisite pairs, where each pair [a,b] indicates course a requires course b to be completed

Given an array of coin denominations and a target amount, find the minimum number of coins needed to make up that amount, or return -1 if it''s impossible.

Given a 2D board of characters and a list of words, find all words from the list that can be formed by sequentially adjacent letters on the board, where each ce

Fill each empty room with the distance to its nearest gate, where rooms are represented by a 2D grid with gates (0), walls (-1), and empty rooms (INF).

Find the number of unique paths from the top-left corner to the bottom-right corner of an m x n grid, where you can only move right or down.

Given an elevation map represented by an array of non-negative integers, calculate how much water can be trapped after raining.

Given a 2D board containing ''X'' and ''O'', capture all regions of ''O'' that are completely surrounded by ''X'' by flipping them to ''X''. Regions connected t

Given an integer array, determine if it can be partitioned into two subsets with equal sum.

Find all cells in a 2D matrix where rainwater can flow to both the Pacific Ocean (left and top edges) and Atlantic Ocean (right and bottom edges), where water f

Find the minimum window substring in string s that contains all characters of string t. If no such window exists, return an empty string.

Find the median of two sorted arrays without merging them into a single array. The overall run time complexity should be O(log (m+n)).

Given the root of a binary tree, return its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthe

Given a string, find and return the longest contiguous substring that reads the same forwards and backwards (palindrome).

Given an array of non-negative integers where each element represents the maximum jump length from that position, determine if you can reach the last index star

Find the maximum amount of money you can rob from houses arranged in a circle, where you cannot rob two adjacent houses and the first and last houses are neighb

Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2. The allowed operations are insert, delete, or rep

Given cars at different positions with different speeds all heading to the same target, determine how many car fleets will arrive at the target. Cars form a fle

Given a list of words from an alien language sorted lexicographically, determine the order of letters in the alien alphabet. Return the alien dictionary as a st

Given a string s and a dictionary of words wordDict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.

Find two numbers in a sorted array that add up to a specific target value, returning their 1-indexed positions.

Given an integer array nums and a target integer, find the number of ways to assign ''+'' or ''-'' signs to each element so that the sum equals the target.