LeetCode 2: Add Two Numbers from Naive to Optimal Carry Simulation
Subtitle / Summary This problem is just grade-school addition on a linked list: add one digit at a time, propagate carry, and append one final node if carry remains after both lists end. We move from naive ideas to the optimal one-pass solution, then map it to real engineering scenarios. Reading time: 12-15 min Tags: linked list, carry, simulation, LeetCode 2 SEO keywords: Add Two Numbers, LeetCode 2, reverse-order list, carry, dummy node Meta description: Use dummy + tail + carry to sum two reverse-order linked lists in O(max(m,n)) time, with common pitfalls, engineering analogies, and six-language runnable implementations. Target Readers Beginners building a stable template for linked-list problems Intermediate developers who often miss carry or boundary cases Engineers who want to transfer algorithmic thinking to stream-style data processing Background / Motivation This looks like an entry-level LeetCode problem, but it trains practical skills you will reuse: ...