LeetCode 1 - Two Sum - 2023.09.29 solution

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        """ Sort the array and then work inwards from the outer ends:
        constant memory and nlogn time.

        Use a dict to keep track of seen numbers, and if you find a match,
        return that: constant time and o(n) memory.

        """
        seen_nums = dict()

        for i, num in enumerate(nums):
            difference = target - num
            if difference in seen_nums:
                return seen_nums[difference], i

            seen_nums[num] = i