Dot product of sparse vectors

class SparseVector:
    def __init__(self, nums: List[int]):
        self.hashmap = {}
        for ind, num in enumerate(nums):
            self.hashmap[ind] = num

    # Return the dotProduct of two sparse vectors
    def dotProduct(self, vec: 'SparseVector') -> int:
        keys1 = list(self.hashmap.keys())
        keys2 = list(vec.hashmap.keys())
        values1 = list(self.hashmap.values())
        values2 = list(vec.hashmap.values())

        result = 0
        i, j = 0, 0

        while(i < len(keys1) and j < len(keys2)):
            if keys1[i] < keys2[j]:
                i += 1
            elif keys1[i] > keys2[j]:
                j += 1
            else:
                result += values1[i] * values2[j]
                i += 1
                j += 1

        return result