[PAT]1009 Product of Polynomials （25 分）Java

This time, you are supposed to find A×BA imes BA×B where AAA and BBB are two polynomials.

Input Specification:

Each input file contains one test case. Each case occupies 2 lines, and each line contains the information of a polynomial:

KKK N1N_1N​1​​aN1a_{N_1}a​N​1​​​​N2N_2N​2​​aN2a_{N_2}a​N​2​​​​ ... NKN_KN​K​​aNKa_{N_K}a​N​K​​​​

where KKK is the number of nonzero terms in the polynomial, NiN_iN​i​​ and aNia_{N_i}a​N​i​​​​ (i=1,2,⋯,Ki=1, 2, cdots , Ki=1,2,⋯,K) are the exponents and coefficients, respectively. It is given that 1≤K≤101le K le 101≤K≤10, 0≤NK<⋯<N2<N1≤10000 le N_K < cdots < N_2 < N_1 le 10000≤N​K​​<⋯<N​2​​<N​1​​≤1000.

Output Specification:

For each test case you should output the product of AAA and BBB in one line, with the same format as the input. Notice that there must be NO extra space at the end of each line. Please be accurate up to 1 decimal place.

Sample Input:

2 1 2.4 0 3.2
2 2 1.5 1 0.5

Sample Output:

3 3 3.6 2 6.0 1 1.6

package pattest;

import java.util.Scanner;

/**
 * @Auther: Xingzheng Wang
 * @Date: 2019/2/18 21:38
 * @Description: pattest
 * @Version: 1.0
 */
public class PAT1009 {
    public static void main(String[] args) {
        int k1, k2, count = 0;
        double[] a = new double[1001];
        double[] b = new double[2001];
        Scanner sc = new Scanner(System.in);
        k1 = sc.nextInt();
        for (int i = 0; i < k1; i++) {
            int index = sc.nextInt();
            a[index] = sc.nextDouble();
        }
        k2 = sc.nextInt();
        for (int i = 0; i < k2; i++) {
            int index = sc.nextInt();
            double s = sc.nextDouble();
            for (int j = 0; j < 1001; j++) {
                if (a[j] != 0) {
                    b[index + j] += s * a[j];
                }
            }
        }
        for (int i = 0; i < 2001; i++) {
            if (b[i] != 0)
                count++;
        }
        System.out.print(count);
        for (int i = 2000; i >= 0; i--) {
            if (b[i] != 0)
                System.out.printf(" %d %.1f", i, b[i]);
        }
    }
}