3Sum

Two pointers · Fix one value, solve a two-sum range · Stretch · about 30 min

Why it matters

This is a good test of pattern recognition, sorting, and duplicate handling.

How it connects

You know two pointers on a sorted range. Fix one number, then use that pattern on the rest.

Try first

After sorting, what two-sum target remains when nums[i] is fixed?

Interview cue

Sorting lets each fixed value use a linear two-pointer sweep while avoiding duplicate triplets.