Back

Two Sum

easy

Given an array of integers nums and an integer target, return the indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

Test Cases

Copy an input into the main harness and Run to verify
Input
nums = [2,7,11,15], target = 9
Expected Output
[0,1]

Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Input
nums = [3,2,4], target = 6
Expected Output
[1,2]
Input
nums = [3,3], target = 6
Expected Output
[0,1]

Constraints

  • 2 <= nums.length <= 10^4
  • -10^9 <= nums[i] <= 10^9
  • -10^9 <= target <= 10^9
  • Only one valid answer exists.

Hints

Hint 1 — click to reveal

A brute force solution checks every pair in O(n^2). Can a hash map reduce this?

Hint 2 — click to reveal

As you iterate, store each number's index. For the current number x, have you already seen target - x?

Java Compiler

Powered by OneCompiler. Starter code loads automatically — edit and hit Run.