Two Sum

Easy

Two Pointers

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

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

Example 1

Input: nums = [2,7,11,15], target = 9

Output: [0,1]

Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Example 2

Input: nums = [3,2,4], target = 6

Output: [1,2]

Explanation: Because nums[1] + nums[2] == 6, we return [1, 2].

Example 3

Input: nums = [3,3], target = 6

Output: [0,1]

Constraints

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

Show Hints (3)

Hint 1: A brute force approach would be to check every pair of numbers. Can you think of a more efficient solution?

Hint 2: What if you could remember what numbers you've seen before? What data structure would help?

Hint 3: For each number, you're looking for its complement (target - current number). A hash map can tell you instantly if you've seen it.

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Test Results

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