src.two_sum

Classes

Solution()

class src.two_sum.Solution

twoSum(nums: list[int], target: int) → list[int]

Thought process

• We create a dictionary to store value -> index

• We recognize the property a + b = target -> target - a = b -> ans = [idx(target - a), idx(a)]

• Since we now only need the current element and target, we can simply:

• iterate through the list

• compute the difference

• see if the difference is in the dictionary

Notes

• time complexity: O(n)

• space complexity: O(n)