余弦相似度

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:
cosine-similarity
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]).
您在真实的面试中是否遇到过这个题？ Yes
样例
给出 A = [1, 2, 3], B = [2, 3 ,4].
返回 0.9926.
给出 A = [0], B = [0].

返回 2.0000

import java.text.DecimalFormat;import java.util.Scanner;/** * 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 SimilarityHere is the formula:cosine-similarityGiven 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]).您在真实的面试中是否遇到过这个题？ Yes样例给出 A = [1, 2, 3], B = [2, 3 ,4].返回 0.9926.给出 A = [0], B = [0].返回 2.0000 *  * @author Dell * */public class Test445 {   public static double cosineSimilarity(int[]A, int[]B)   {       int sum=0;   for(int i=0;i<A.length;i++)   {   sum=sum+A[i]*B[i];   }   int sumA=0;   int sumB=0;   for(int i=0;i<A.length;i++)   {   sumA=sumA+A[i]*A[i];   }   if(sumA==0)   return 2.0000;   for(int i=0;i<B.length;i++)   {   sumB=sumB+B[i]*B[i];   }   if(sumB==0)   return 2.0000;   return sum/(Math.sqrt(sumA)*Math.sqrt(sumB));   }public static void main(String[] args) {     Scanner sc=new Scanner(System.in);     int n=sc.nextInt();     int[] a=new int[n];     for(int i=0;i<a.length;i++)     {     a[i]=sc.nextInt();     }     int[] b=new int[n];     for(int i=0;i<b.length;i++)     {     b[i]=sc.nextInt();     }     double result=cosineSimilarity(a,b);     DecimalFormat df=new DecimalFormat("0.0000");     System.out.println(df.format(result));}}