Suppose, we have two sparse vectors represented in two lists. We have to return the dot product of the two sparse vectors. The vectors are represented as objects, and the lists are stored in a member variable 'nums' in the objects.
So, if the input is like vector1 = [1, 0, 0, 0, 1], vector2 = [0, 0, 0, 1, 1], then the output will be 1 The dot product is 1 * 0 + 0 * 0 + 0 * 0 + 0 * 1 + 1 * 1 = 1.
To solve this, we will follow these steps −
res := 0
for each index i, value v in nums of vector2, do
if v is same as 0, then
continue
otherwise when nums[i] of vector1 is same as 0, then
go for next iteration
otherwise,
res := res + v * nums[i] of vector1
return res
Example (Python)
Let us see the following implementation to get better understanding −
class Solution: def __init__(self, nums): self.nums = nums def solve(self, vec): res = 0 for i, v in enumerate(vec.nums): if v == 0: continue elif self.nums[i] == 0: continue else: res += v * self.nums[i] return res ob1, ob2 = Solution([1, 0, 0, 0, 1]), Solution([0, 0, 0, 1, 1]) print(ob1.solve(ob2))
Input
[1, 0, 0, 0, 1], [0, 0, 0, 1, 1]
Output
1