TwoSum.py

class Solution(object):
    def twoSum(self, nums, target):
        hashtable = {}

        for i in range(len(nums)):
            if nums[i] in hashtable and nums[i]*2 == target : #edge case when target is the sum of 2 identical numbers
                return [hashtable[nums[i]], i]
            hashtable[nums[i]] = i

        for x in range(len(nums)):
            complementary = target-nums[x]
            if complementary in hashtable and complementary != nums[x]:   #checks if target - number in list is another number in list and to not use same number and index twice
                return [hashtable[complementary],x]