Arrays

Arrays

Two Sums

class Solution(object):
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        complement_index = {}

        for i, n in enumerate(nums):
            print(i, n)
            complement = target - n
            print(complement)
            complement_index[complement] = i

        for i, n in enumerate(nums):
            if n in complement_index and i != complement_index[n]:
                print(n)
                return [i, complement_index[n]]

• Key insight: Figure out the complement for each value in nums, and then store that complement in a dictionary, wit the index of that value. After, iterate through nums again and see if n is in our complement_index dict (which means we found a complement). If so, return our current index of the complement, plus the index of the original value from our first scan. Make sure that both of these indexes aren't the same value.