DSA
Solved problems,
Solved problems,
pattern first.
Python solutions with explanations, reusable patterns, and production context where it helps.
Browse by difficulty
34 total Filter the collection without changing the page structure.
Browse by topic
#1 Two Sum
ArrayHash Map
Easy → #4 Median Of Two Sorted Arrays ArrayBinary SearchDivide and Conquer
Hard → #20 Valid Parentheses StackString
Easy → #33 Search Rotated Sorted Array Binary SearchArray
Medium → #42 Trapping Rain Water ArrayTwo PointersStack
Hard → #46 Permutations BacktrackingArray
Medium → #53 Maximum Subarray ArrayDynamic Programming
Medium → #62 Unique Paths Dynamic ProgrammingMath
Medium → #63 Unique Paths II Dynamic Programming
Medium → #70 Climbing Stairs Dynamic Programming
Easy → #72 Min Distance StringDynamic Programming
Medium → #76 Minimum Window Substring StringHash MapSliding Window
Hard → #84 Largest Rectangle In Histogram ArrayStackMonotonic Stack
Hard → #104 Maximum Depth Binary Tree Binary TreeDFSBFSRecursion
Easy → #121 Best Time To Buy And Sell ArrayTwo PointersGreedy
Easy → #124 Binary Tree Maximum Path Sum Binary TreeDFSRecursion
Hard → #125 Valid Palindrome StringTwo Pointers
Easy → #128 Longest Consecutive Sequence ArrayHash Map
Medium → #136 Single Number Bit ManipulationArray
Easy → #200 Number Of Islands GraphDFSBFSMatrix
Medium → #206 Reverse Linked List Linked ListRecursion
Easy → #207 Course Schedule GraphTopological SortDFSBFS
Medium → #208 Implement Trie TrieDesignHash Map
Medium → #215 Kth Largest Element HeapQuick SelectSorting
Medium → #217 Contains Duplicate ArrayHash Map
Easy → #239 Sliding Window Maximum ArraySliding WindowQueueMonotonic Queue
Hard → #242 Valid Anagram StringHash Map
Easy → #295 Find Median From Data Stream HeapDesignSorting
Hard → #516 Longest Palindrome Subsequence StringDynamic Programming
Medium → #547 Number Of Provinces Union-FindGraphDFS
Medium → #647 Palindrome Substrings StringDynamic Programming
Medium → #746 Min Cost Climbing Stairs Dynamic Programming
Easy → #1143 Longest Common Subsequence StringDynamic Programming
Medium → #1299 Replace With Greatest On Right ArraySliding Window
Medium →