1009 Product of Polynomials

This time, you are supposed to find A×B where A and B 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:

K N​1​​ a​N​1​​​​ N​2​​ a​N​2​​​​ ... N​K​​ a​N​K​​​​

where K is the number of nonzero terms in the polynomial, N​i​​ and a​N​i​​​​ (,) are the exponents and coefficients, respectively. It is given that 1, 0.

Output Specification:

For each test case you should output the product of A and B 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

注意！如果系数为0则必须清除！！！这也是0测试点不通过的原因。

import java.util.*;

public class Main{
    static Map<Integer,Double> Map1;
    static Map<Integer,Double> Map2;
    static Map<Integer,Double> Map3;
    static int[] index1;
    static int[] index2;
    static int Max = 0;
    static int Min = 10000;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Map1 = new HashMap<>();
        Map2 = new HashMap<>();
        Map3 = new HashMap<>();
        int K = sc.nextInt();
        for(int i=0;i<K;i++) {
            Map1.put(sc.nextInt(),sc.nextDouble());
        }
        K = sc.nextInt();
        for(int i=0;i<K;i++) {
            Map2.put(sc.nextInt(),sc.nextDouble());
        }
        sc.close();
        Iterator<Integer> it= Map1.keySet().iterator();
        while(it.hasNext()) {
            int now1 = it.next();
            Iterator<Integer> it2 = Map2.keySet().iterator();
            while(it2.hasNext()) {
                int now2 = it2.next();
                int now3 = now1+now2;
                if(now3>Max) Max=now3;
                if(now3<Min) Min =now3;
                Double res = Map1.get(now1)*Map2.get(now2);
                if(Map3.containsKey(now3)) {
                    res+=Map3.get(now3);
                    Map3.put(now3,res);
                    if(Map3.get(now3)==0) Map3.remove(now3);
                }else {
                    Map3.put(now3,res);
                    if(Map3.get(now3)==0) Map3.remove(now3);
                }
            }
        }
        System.out.print(Map3.size()+" ");
        for(int i=Max;i>Min-1;i--) {
            if(Map3.containsKey(i)) {
                if(i==Min)
                    System.out.print(i+" "+String.format("%.1f",Map3.get(i)));
                else
                    System.out.print(i+" "+String.format("%.1f",Map3.get(i))+" ");
            }
        }
    }
}