ThomasHigginson

def threeSum(self, nums: List[int]) -> List[List[int]]:
    if len(nums) < 3: # Requires 3 for a pair of 3
        return []
    elif len(nums) == 3 and sum(nums) == 0: # Naive case; check sum of 3 elements
        return [nums]

    nums = sorted(nums) # O(nlogn)

    solutions = []
    i = 0

ThomasHigginson

def twoSum(self, nums: List[int], target: int) -> List[int]:
    number2Index = {} # Lookup table for observed number to it's index

    # 1. Get a given numbers complement
    # 2. If it's in number2Index, then it's complement
    # exists, and return it's index along with the complement's index
    # 3. Otherwise, add this number as a key, and it's index as the value
    for idx, num in enumerate(nums):
        numComplement = target - num
        if numComplement in number2Index: