Algorithm Atlas

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Learn Tree with visual DSA lessons

Learn Tree with 4 DSA patterns and 39 visual lessons. Follow step-by-step animations and synced C#, Python, and Java code.

A tree begins at a root and branches into child nodes.

DFS Traversals

Explore one branch deeply before returning to another branch.

Inorder Traversal Easy · Visible node journey
Preorder Traversal Easy · Visible node journey
Postorder Traversal Easy · Visible node journey
Same Tree Check (DFS variant) Easy · Visible node journey
Symmetric Tree Easy · Visible node journey
Diameter of Binary Tree Easy · Visible node journey
Balanced Binary Tree Easy · Visible node journey
Maximum Depth of Binary Tree Easy · Visible node journey
Minimum Depth of Binary Tree Easy · Visible node journey
Subtree of Another Tree Easy · Visible node journey
Path Sum Easy · Visible node journey
Path Sum II Medium · Visible node journey
Path Sum III Medium · Visible node journey
Print All Nodes at Distance K Medium · Visible node journey
Boundary Traversal of a Binary Tree Medium · Visible node journey
Count Complete Tree Nodes Medium · Visible node journey
Binary Tree Maximum Path Sum Hard · Visible node journey
Binary Tree Cameras Hard · Visible node journey

BFS / Level-Order

Use a queue to visit the tree one horizontal level at a time.

Binary Tree Level Order Traversal Medium · Visible node journey
Binary Tree Zigzag Level Order Traversal Medium · Visible node journey
Average of Levels in Binary Tree Easy · Visible node journey
Cousins in Binary Tree Easy · Visible node journey
Left Side View Easy · Visible node journey
Binary Tree Right Side View Medium · Visible node journey
Populating Next Right Pointers in Each Node Medium · Visible node journey
Vertical Order Traversal Medium · Visible node journey
Top View of a Binary Tree Medium · Visible node journey
Bottom View of Binary Tree Medium · Visible node journey
Maximum Width of Binary Tree Medium · Visible node journey

Lowest Common Ancestor

Find the lowest node whose subtree contains both targets.

Lowest Common Ancestor of Binary Tree Medium · Visible node journey
Find Distance Between Nodes Medium · Visible node journey
Kth Ancestor of a Tree Node Hard · Visible node journey

Serialization / Construction

Encode, rebuild, invert, flatten, or reconnect a tree.

Invert Binary Tree Easy · Visible node journey
Flatten Binary Tree to Linked List Medium · Visible node journey
Construct Binary Tree from Preorder & Inorder Medium · Visible node journey
Populating Next Right Pointers Medium · Visible node journey
Construct Binary Tree from Inorder and Postorder Traversal Medium · Visible node journey
Construct Binary Tree from Preorder and Postorder Traversal Medium · Visible node journey
Serialize and Deserialize Binary Tree Hard · Visible node journey