PAT 甲级【1009 Product of Polynomials】

/*

1. 系数为0不输出
2. 貌似runtime异常也显示答案不正确
   
   */

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StreamTokenizer;

public class Main {
    @SuppressWarnings("unchecked")
    public static void main(String[] args) throws IOException {
        StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        in.nextToken();
        int n = (int) in.nval;
        int[] N = new int[n];
        double[] a = new double[n];
        for (int i = 0; i < n; i++) {
            in.nextToken();
            N[i] = (int) in.nval;
            in.nextToken();
            a[i] = in.nval;
        }
        in.nextToken();
        int m = (int) in.nval;
        int[] M = new int[m];
        double[] b = new double[m];
        for (int i = 0; i < m; i++) {
            in.nextToken();
            M[i] = (int) in.nval;
            in.nextToken();
            b[i] = in.nval;
        }
        double[] map = new double[N[0] + M[0]+1];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                map[N[i] + M[j]] += a[i] * b[j];
            }
        }
        int k = 0;
        for (int i = N[0] + M[0]; i >= N[n - 1] + M[m - 1]; i--) {
            if (Math.abs(map[i]) > 0.0001) {
                k++;
            }
        }
        System.out.print(k);
        for (int i = N[0] + M[0]; i >= N[n - 1] + M[m - 1]; i--) {
            if (Math.abs(map[i]) > 0.0001) {
                System.out.print(String.format(" %d %.1f", i, map[i]));
            }
        }
        System.out.println();
    }
}