1582 articles
LC 138 Copy List with Random Pointer is a medium interview problem at Amazon, Microsoft, and Facebook that requires deep-copying a linked list where each node has a random pointer. Learn the O(n) space hash map approach and the clever O(1) space interleave technique with Python and JavaScript solutions and detailed dry run.
LC 430 Flatten a Multilevel Doubly Linked List is a medium interview problem at Microsoft and Amazon that uses DFS or an explicit stack to inline child sub-lists into the main list. Learn the iterative stack approach and the recursive approach with Python and JavaScript, step-by-step dry run, and interview tips.
LC 142 Linked List Cycle II is a medium interview problem at Amazon, Microsoft, and Google where you find the exact node where a cycle begins using Floyd's algorithm and a mathematical proof. Learn the two-phase approach with Python and JavaScript, the math proof, visual dry run, and common interview questions.
LC 287 Find the Duplicate Number is a brilliant medium interview problem at Amazon, Google, and Facebook where you find a duplicate in an n+1 integer array in O(1) space by treating the array as an implicit linked list and applying Floyd's cycle detection algorithm. Master the connection between arrays and linked lists with Python and JavaScript solutions and detailed proof.
Complete cheatsheet for Linked Lists: all 7 patterns, template code, Big O reference, and MAANG interview priority guide.