depth first search

Word Search

Solve Word Search with backtracking by exploring adjacent cells to match a target word in a grid.

Binary Tree Inorder Traversal

Binary Tree Inorder Traversal asks you to visit left subtree, node, then right subtree without losing position while mov…

Validate Binary Search Tree

Validate Binary Search Tree problem checks if a binary tree satisfies BST properties using tree traversal and state trac…

Recover Binary Search Tree

Recover a BST where two nodes are swapped by mistake using in-order traversal and careful state tracking to restore corr…

Same Tree

Check whether two binary trees are identical by comparing structure and node values using DFS or BFS traversal strategie…

Symmetric Tree

Determine if a binary tree is symmetric by comparing left and right subtrees using DFS or BFS traversal techniques effic…

Maximum Depth of Binary Tree

Find the maximum depth of a binary tree using traversal techniques to track the longest path from root to leaf.

Balanced Binary Tree

Determine if a binary tree is height-balanced using tree traversal and state tracking techniques.

Minimum Depth of Binary Tree

Find the minimum depth of a binary tree, which is the shortest path from the root node to the nearest leaf node.

Path Sum

Determine if a binary tree has a root-to-leaf path where the sum of node values equals a given target sum, using DFS or …

Path Sum II

Find all root-to-leaf paths in a binary tree where the sum of node values equals a given target using DFS backtracking.

Flatten Binary Tree to Linked List

Flatten a binary tree into a right-skewed linked list by manipulating pointers following a pre-order traversal, handling…

Populating Next Right Pointers in Each Node

Connect each node across every level by reusing established next links to traverse a perfect binary tree without extra q…

Populating Next Right Pointers in Each Node II

Populate each next pointer in a binary tree to its immediate right node, handling nulls and uneven levels efficiently us…

Binary Tree Maximum Path Sum

Calculate the maximum sum of any path in a binary tree by exploring all node sequences using DFS and dynamic programming…

Sum Root to Leaf Numbers

Calculate the sum of all root-to-leaf numbers in a binary tree where each path represents a number.

Surrounded Regions

Transform the matrix in-place by marking regions surrounded by 'X' as 'X', while keeping border-adjacent 'O's intact.

Clone Graph

Clone Graph involves cloning a graph using DFS, focusing on graph traversal and neighbor management using hash tables.

Binary Tree Preorder Traversal

Perform a binary tree preorder traversal by visiting root nodes first, then left and right subtrees, tracking state iter…

Binary Tree Postorder Traversal

Solve Binary Tree Postorder Traversal using state tracking and binary-tree traversal techniques, focusing on Stack, Tree…

Binary Tree Right Side View

The Binary Tree Right Side View problem asks you to return the visible nodes from the right side of a binary tree, trave…

Number of Islands

Count the number of distinct islands in a binary grid using array traversal combined with depth-first search exploration…

Course Schedule II

Solve the 'Course Schedule II' problem using graph indegree and topological ordering, utilizing DFS or BFS to find the c…

Design Add and Search Words Data Structure

Build a WordDictionary supporting dynamic word addition and search with wildcard matching efficiently using Trie and DFS…