Two Sum
Easy
Array
Hash Table
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]
Example 3
Input: nums = [3,3], target = 6
Output: [0,1]

Constraints

  • •2 <= nums.length <= 10⁴
  • •-10⁹ <= nums[i] <= 10⁹
  • •-10⁹ <= target <= 10⁹
  • •Only one valid answer exists.
Time Complexity
O(n)
Space Complexity
O(n)
14
Case 1
Input: [2,7,11,15] 9
Expected: [0,1]
Case 2
Input: [3,2,4] 6
Expected: [1,2]
Case 3
Input: [3,3] 6
Expected: [0,1]