AlgorithmsTopicsAlgorithm topics14 topics covering 53 curated problems. Pick one to see when to use it, how to spot it, a code template and practice problems.Results5 problemsHash MapCount frequency, check if seen beforeEasy (3)Medium (2)Open topic 5 problemsTwo PointersScan a sorted array from both endsEasy (1)Medium (3)Hard (1)Open topic 4 problemsSliding WindowFind a contiguous subarray meeting a conditionEasy (1)Medium (3)Open topic 4 problemsStackLast-in first-out: brackets, undoEasy (1)Medium (3)Open topic 3 problemsLinked ListNodes linked in a chain, fast head opsEasy (3)Open topic 3 problemsPrefix SumPrecompute running sums, answer range queries instantlyEasy (1)Medium (2)Open topic 4 problemsBinary SearchSearch fast in sorted dataEasy (2)Medium (2)Open topic 3 problemsBFS (Breadth-First Search)Shortest path, level-by-level traversalMedium (2)Hard (1)Open topic 4 problemsDFS (Depth-First Search)Traverse trees and graphs deeply, find cyclesEasy (1)Medium (3)Open topic 4 problemsIntervalsMerge overlapping time rangesEasy (1)Medium (3)Open topic 4 problems1D Dynamic ProgrammingCache subproblem results, skip recomputeEasy (1)Medium (3)Open topic 4 problemsGreedyPick the best choice at each stepEasy (1)Medium (3)Open topic 3 problemsBacktrackingList every combination and permutationMedium (3)Open topic 3 problemsHeapGrab max/min fast, find the top KMedium (1)Hard (2)Open topic
