1. Two Sum

You are interviewing for a backend software engineer role at a FAANG-level technology company.
The interviewer presents a real-world system scenario instead of a textbook question.

A large-scale platform processes numerical data such as:

• Transaction amounts
• Inventory weights
• Ad bidding values
• System performance metrics

For analytics and optimization, the system frequently needs to identify two distinct values whose sum equals a specific target value.

Your Task

Given:

• An integer array nums
• An integer target

Return the indices of the two distinct elements in nums whose sum equals target.

Important Rules

• Each element can be used only once
• Exactly one valid solution exists
• Return the indices, not the values
• Indices may be returned in any order
• The solution must be efficient and scalable

This is a common practice coding problem for DSA question in Google, Amazon, Netflix, Meta, Apple, Microsoft, Uber, and Bloomberg interviews.

Examples

Constraints

• 2 <= nums.length <= 100,000
• -10^9 <= nums[i] <= 10^9
• -10^9 <= target <= 10^9
• Exactly one valid solution exists
• Output indices can be returned in any order