🔗 Dot Product

Two one-dimensional integer arrays a and b of equal length are given as parameters. Complete the solution function so that it returns the dot product of a and b.

Here, the dot product of a and b is a[0] * b[0] + a[1] * b[1] + ... + a[n-1] * b[n-1]. (n is the length of a and b)

• The length of a and b is between 1 and 1,000 inclusive.
• Every number in a and b is between -1,000 and 1,000 inclusive.

Input/Output Example #1

The dot product of a and b is 1 * (-3) + 2 * (-1) + 3 * 0 + 4 * 2 = 3.

Input/Output Example #2

The dot product of a and b is (-1) * 1 + 0 * 0 + 1 * (-1) = -2.

We just need to iterate over the index, multiply the corresponding elements of a and b, and accumulate the values. Since a and b are the same length, either array can be used for indexing.

JAVA
for (int i = 0; i < a.length; i++)
{
	answer += a[i] * b[i];
}

As shown above, accumulate the product of each pair of elements into answer.

JAVA
/**
 * Dot Product class
 *
 * @author RWB
 * @since 2021.12.10 Fri 00:17:10
 */
class Solution
{
	/**
	 * Method that returns the answer
	 *
	 * @param a: [int[]] Integer array
	 * @param b: [int[]] Integer array
	 *
	 * @return [int] The answer
	 */
	public int solution(int[] a, int[] b)
	{
		int answer = 0;
		
		for (int i = 0; i < a.length; i++)
		{
			answer += a[i] * b[i];
		}
		
		return answer;
	}
}