Skip to main content

1. Two Sum

easyAsked at Squarespace

Find two indices whose values sum to a target; Squarespace uses it as a phone-screen warm-up to gauge JS hash-map fluency.

By Alex Chen, Founder, InterviewChamp.AI · Last verified

Problem

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. Each input has exactly one solution and you may not use the same element twice.

Constraints

  • 2 <= nums.length <= 10^4
  • -10^9 <= nums[i], target <= 10^9

Examples

Example 1

Input
nums=[2,7,11,15], target=9
Output
[0,1]

Example 2

Input
nums=[3,2,4], target=6
Output
[1,2]

Approaches

1. Brute force

Nested loops scan every pair.

Time
O(n^2)
Space
O(1)
for (let i=0;i<n;i++) for (let j=i+1;j<n;j++) if (nums[i]+nums[j]===target) return [i,j];

Tradeoff:

2. Hash map

One pass storing complements gives O(n).

Time
O(n)
Space
O(n)
function twoSum(nums, target) {
  const seen = new Map();
  for (let i = 0; i < nums.length; i++) {
    const c = target - nums[i];
    if (seen.has(c)) return [seen.get(c), i];
    seen.set(nums[i], i);
  }
}

Tradeoff:

Squarespace-specific tips

Squarespace interviewers want clean ES6 Map usage and a quick callout that the same complement-lookup pattern shows up in their template-block ID resolution code.

Solve it now

Free. No sign-up. Python and JavaScript run instantly in your browser.

Output

Press Run or Cmd+Enter to execute

Practice these live with InterviewChamp.AI

Drill Two Sum and other Squarespace interview questions under real-loop conditions with instant feedback on your reasoning, complexity claims, and code.

Practice these live with InterviewChamp.AI →