最佳拟合直线

import java.util.Scanner;public class Main {public static void main(String[] args) {// TODO Auto-generated method stubScanner cin = new Scanner(System.in);while (cin.hasNext()) {int n = cin.nextInt();            int[] x=new int[n];            int[] y=new int[n];for (int i = 0; i < n; i++) {                x[i]=cin.nextInt();                y[i]=cin.nextInt();}int fx=sum(x);int fy=sum(y);int fxy=sum(x,y);int fxx=sum(x,x);double a=(double)(n*fxy-fx*fy)/(n*fxx-fx*fx);double b=(double)(fy*fxx-fx*fxy)/(n*fxx-fx*fx);System.out.println(String.format("%.3f",a));System.out.println(String.format("%.3f",b));}cin.close();}public static int sum(int[]...  arr){int len=arr.length ;int deeplen=arr[0].length;@SuppressWarnings("unused")int sum=0;for(int i=0;i<deeplen;i++){if(len==1){sum+=arr[0][i];}else if(len==2){sum+=arr[0][i]*arr[1][i];}}return sum;}}