Problem Statement

At Lyft, you are given an unsorted list of integers and a target value. Return the indices of the two distinct elements whose sum equals the target.

Formal Specification

Implement a function that takes:

• nums: a list of integers
• target: an integer

Return:

• A list of two integers [i, j] where i != j and nums[i] + nums[j] == target

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

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

Example 3

• Input: nums = [3, 3], target = 6
• Output: [0, 1]
• Explanation: The two different indices contain the same value, which is allowed.

Constraints

• 2 <= len(nums) <= 10^5
• -10^9 <= nums[i] <= 10^9
• -10^9 <= target <= 10^9
• Exactly one valid answer exists
• Return indices in the order they are found by your algorithm