Two Sum

Given an array of integers nums and an integer target, return the indices of the two numbers that add up to target.

You may assume exactly one valid answer exists, and you may not use the same element twice. Return the indices in any order.

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Example 1

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

Example 2

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

Example 3

Input: nums = [3, 3], target = 6
Output: [0, 1]
Explanation: nums[0] + nums[1] = 3 + 3 = 6; the same value can appear at two different indices.

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Constraints

• 2 <= nums.length <= 10^4
• -10^9 <= nums[i] <= 10^9
• -10^9 <= target <= 10^9
• Exactly one valid answer exists.