3Sum
LeetCode 15 • Medium • Two Pointers
Input: nums = [-2, -1, 0, 1, 2] → Output: [[-2,0,2], [-1,0,1]]
Find all unique triplets that sum to zero. Sort first, then fix i and two-pointer on the rest.
TimeO(n²)outer loop + two-pointer pass
SpaceO(1)or O(log n) for sort
i: —
Target: —
Triplets: 0
Fixed (i)
Left
Right
Found triplet
i
—
Left
—
Right
—
Result
—