Cosine Similarity Show result

26% Accepted

Cosine similarity is a measure of similarity between two vectors of an inner product space that measures the cosine of the angle between them.
The cosine of 0° is 1, and it is less than 1 for any other angle.

See wiki: Cosine Similarity

Here is the formula:


Given two vectors A and B with the same size, calculate the cosine similarity.

Return 2.0000 if cosine similarity is invalid (for example A = [0] and B = [0]).

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Example
Given A = [1, 2, 3], B = [2, 3 ,4].

Return 0.9926.

Given A = [0], B = [0].

Return 2.0000

class Solution {
    /**
     * @param A: An integer array.
     * @param B: An integer array.
     * @return: Cosine similarity.
     */
    public double cosineSimilarity(int[] A, int[] B) {
        // write your code here
        if (A == null || B == null || A.length != B.length) {
            return 2.0000;
        }
        double molecule = 0;
        double denominatorA = 0;
        double denominatorB = 0;

        for (int i = 0; i < A.length; i++) {
            molecule = molecule + A[i] * B[i];
            denominatorA = denominatorA + A[i] * A[i];
            denominatorB = denominatorB + B[i] * B[i];
        }
        if (denominatorA == 0 || denominatorB == 0) {
            return 2.0000;
        }

        denominatorA = Math.sqrt(denominatorA);
        denominatorB = Math.sqrt(denominatorB);

        return molecule / (denominatorA * denominatorB);

    }
}