Code Room
CodingMediumcod-g322
Subject Two pointersLevel Mid–Senior~26 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given an array nums and an integer target, count the number of index triples (i, j, k) with i < j < k such that nums[i] + nums[j] + nums[k] < target. Constraints: 0 <= len(nums) <= 3500, -100 <= nums[i] <= 100, -3*10^4 <= target <= 3*10^4. Aim for O(n^2).

Implement
three_sum_smaller(nums: list[int], target: int) → int
Examples
in[[-2,0,1,3],2]out2
What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.