Two Sum

Problem Preview

"### Problem 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 <= 10^4 * -10^9 <= nums[i] <= 10^9 * -10^9 <= target <= 10^9 * Only one valid answer exists."