Two Sum

Problem Return the indices of the two numbers in nums that add up to target. Exactly one valid answer exists, and an element may not be used twice.

Input / Output

• Input: integer array nums, integer target.
• Output: the pair of indices [i, j] with nums[i] + nums[j] == target.

Constraints

• 2 ≤ nums.length ≤ 10^4
• Values may be negative and may repeat.

Example

• nums = [3,2,4], target = 6 → [1,2].
• nums = [3,3], target = 6 → [0,1].