Problem

At Shopify, a checkout service needs to find two item prices whose sum matches a discount target. Given an array of integers nums and an integer target, return the indices of the two distinct elements whose values add up to target.

You may assume exactly one valid pair exists, and you may not use the same element twice.

Formal Specification

• Input:
  • nums: a list of integers
  • target: an integer
• Output:
  • A list of two integers [i, j] where i != j and nums[i] + nums[j] == target
• The returned indices may be in any order.

Examples

Example 1

• Input: nums = [2, 7, 11, 15], target = 9
• Output: [0, 1]
• Explanation: nums[0] + nums[1] = 2 + 7 = 9

Example 2

• Input: nums = [3, 2, 4], target = 6
• Output: [1, 2]
• Explanation: nums[1] + nums[2] = 2 + 4 = 6

Constraints

• 2 <= len(nums) <= 10^5
• -10^9 <= nums[i] <= 10^9
• -10^9 <= target <= 10^9
• Exactly one valid answer exists