Add Two Numbers

Linked lists · Advance two lists with a carry · Easy · about 24 min

Why it matters

It tests clean pointer work under an easy-to-explain real-world operation.

How it connects

This is the dummy-tail pattern again, with one tiny piece of state carried to the next node.

Try first

What must be included in each digit sum besides the two current node values?

Interview cue

The carry is the only cross-node state; the dummy head handles the result uniformly.