内容纲要
阿里面试题目，根据参数进行回归分析，这里是放假，重点是公式，矩阵类
import java.io.*;
import java.util.Scanner;
import java.math.BigInteger;
import java.util.*;
class Matrix
{
private int row;
private int column;
private double [][] matrix;
Matrix(int r, int c)
{
row = r;
column = c;
matrix = new double[r][c];
}
Matrix(double[][] m, int r, int c)
{
row = r;
column = c;
matrix = m;
}
Matrix(double[][] m)
{
row = m.length;
column = m[0].length;
matrix = m;
}
public int getrow()
{
return row;
}
public int getcolumn()
{
return column;
}
public Matrix ADD(Matrix m)
{
Matrix tmp = new Matrix(row, column);
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
tmp.matrix[i][j] = matrix[i][j] + m.matrix[i][j];
}
}
return tmp;
}
public Matrix SUB(Matrix m)
{
Matrix tmp = new Matrix(row, column);
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
tmp.matrix[i][j] = matrix[i][j] - m.matrix[i][j];
}
}
return tmp;
}
public Matrix MUL(Matrix m)
{
Matrix tmp = new Matrix(row, m.column);
for (int i = 0; i < row; i++)
for (int j = 0; j < m.column; j++)
{
tmp.matrix[i][j] = 0;
for (int k = 0; k < column; k++)
tmp.matrix[i][j] += matrix[i][k] * m.matrix[k][j];
}
return tmp;
}
public Matrix T()
{
Matrix tmp = new Matrix(column, row);
for (int i = 0; i < row; i++)
for (int j = 0; j < column; j++)
{
tmp.matrix[j][i] = matrix[i][j];
}
return tmp;
}
public Matrix getAStar(int h, int v)
{
Matrix tmp = new Matrix(column-1, row-1);
for (int i = 0; i < row-1; i++)
{
if (i < h - 1)
{
for (int j = 0; j < column-1; j++)
{
if (j < v - 1)
{
tmp.matrix[i][j] = matrix[i][j];
}
else
{
tmp.matrix[i][j] = matrix[i][j + 1];
}
}
}
else
{
for (int j = 0; j < column-1; j++)
{
if (j < v - 1)
{
tmp.matrix[i][j] = matrix[i + 1][j];
}
else
{
tmp.matrix[i][j] = matrix[i + 1][j + 1];
}
}
}
}
return tmp;
}
public double getMartrixResult()
{
//二维矩阵计算
if (row == 2)
{
return matrix[0][0] * matrix[1][1] - matrix[0][1] * matrix[1][0];
}
double result = 0;
int num = row;
double[] nums = new double[num];
for (int i = 0; i < row; i++)
{
if (i % 2 == 0)
{
nums[i] = matrix[0][i] * getAStar(1, i + 1).getMartrixResult();
}
else
{
nums[i] = -matrix[0][i] * getAStar(1, i + 1).getMartrixResult();
}
}
for (int i = 0; i < row; i++)
{
result += nums[i];
}
// System.out.println(result);
return result;
}
public Matrix getReverseMartrix()
{
Matrix tmp = new Matrix(row, column);
double A = getMartrixResult();
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
if ((i + j) % 2 == 0)
{
tmp.matrix[i][j] = getAStar(i + 1, j + 1).getMartrixResult() / A;
}
else
{
tmp.matrix[i][j] = -getAStar(i + 1, j + 1).getMartrixResult()/ A;
}
}
}
tmp = tmp.T();
return tmp;
}
public void print()
{
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
if (j == 0)
{
System.out.print(matrix[i][j]);
}
else
System.out.print(" " + matrix[i][j]);
}
System.out.println("");
}
}
}
public class Main
{
public static void main(String args[]) throws FileNotFoundException
{
// Scanner cin = new Scanner(System.in);
InputStream in = new FileInputStream(new File("/Users/sky/Documents/SVN/1.in"));
Scanner cin = new Scanner(in);
int num_of_param, num_of_test, num_of_untest;
double x[][];
double y[][];
double testdata[][];
while (cin.hasNext())
{
num_of_param = cin.nextInt()+1;
num_of_test = cin.nextInt();
x = new double[num_of_test][num_of_param];
y = new double[num_of_test][1];
for (int i = 0; i < num_of_test; i++)
{
for (int j = 1; j < num_of_param; j++)
x[i][j] = cin.nextDouble();
y[i][0]=cin.nextDouble();
}
for (int j=0;j<num_of_test;j++)
x[j][0]=1;
Matrix X = new Matrix(x);
Matrix Y = new Matrix(y);
Matrix B = new Matrix(num_of_test,1);
//B=(XTX)−1XTY
B=X.T().MUL(X).getReverseMartrix().MUL(X.T()).MUL(Y);
num_of_untest=cin.nextInt();
testdata=new double[num_of_untest][num_of_param];
for (int i = 0; i < num_of_untest; i++)
{
for (int j = 1; j < num_of_param; j++)
testdata[i][j] = cin.nextDouble();
}
for (int j=0;j<num_of_untest;j++)
testdata[j][0]=1;
Matrix result=new Matrix(testdata).MUL(B);
result.print();
}
}
}