2Sum

Clarification

The inputs are an integer array nums and an integer target, return the indices of two numbers that add up to target.

Clarifying questions I would ask:

• Are numbers sorted? (Usually no)
• Can there be negative numbers? (Yes)
• Will there be an integer overflow?
• Can I use the same element twice?
• Exactly one solution guaranteed? (Usually yes)
• What should I return if there is no valid answer?