Merge Two Sorted Lists – Solution & Complexity

The optimal Merge Two Sorted Lists solution runs in O(m + n) time and O(1) space. Two pointers splice the smaller next node.

Two pointers splice the smaller next node. This gives O(m + n) time complexity, and is a classic linked list, two pointers, and recursion problem.

We provide a worked Merge Two Sorted Lists solution in Python, JavaScript, Java, Go, Rust, C++ & Ruby with a step-by-step explanation above. You can also open the interactive editor to write and run your own Python solution against the test cases in the browser.

Merge Two Sorted Lists is generally rated Easy. It tests linked list, two pointers, and recursion, which are common coding-interview patterns.