# [Two Sum](https://leetcode.com/problems/two-sum/)
###### tags: `Leetcode`, `Easy`, `Arrays and Hashing`

## Approach
* Initialize a HashMap
* Iterate through every number in list
* diff = target - nums[index]
* if diff is in HashMap - return list of indices
* otherwise add to HashMap: key = nums[index], value = index
* return [] if no match is found for diff

## Asymptotic Analysis
### Time Complexity: **O(n)**
### Space Complexity: **O(n)**

## Code

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        hMap = {}
        for index in range(len(nums)):
            diff = target - nums[index]
            if diff in hMap:
                return [index, hMap[diff]]
            hMap[nums[index]] = index
        return []