Practice

20 DS&A problems with a live Python code runner. For real-world system design problems, see Real World.

DS&A Progress0 / 20 solved
easy: 0/5medium: 0/10hard: 0/5
Palindrome PermutationArrays & Strings
easy
String CompressionArrays & Strings
easy
Remove Dups from Linked ListLinked Lists
easy
Stack MinStacks & Queues
easy
Triple StepRecursion & DP
easy
One AwayArrays & Strings
medium
Rotate MatrixArrays & Strings
medium
Partition Linked ListLinked Lists
medium
Sum ListsLinked Lists
medium
Sort StackStacks & Queues
medium
BFS Path FindingGraphs
medium
Balanced BST from ArrayTrees & BSTs
medium
Magic IndexRecursion & DP
medium
Coin Change (Ways)Recursion & DP
medium
Topological Sort (Build Order)Graphs
medium
Loop DetectionLinked Lists
hard
List of DepthsTrees & BSTs
hard
Validate BSTTrees & BSTs
hard
First Common AncestorTrees & BSTs
hard
Permutations Without DupsRecursion & DP
hard