题干
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 N1 aN1 N2 aN2 … NK aNK
where K is the number of nonzero terms in the polynomial, Niand aNi(i=1,2,⋯,K) are the exponents and coefficients, respectively. It is given that 1≤K≤10, 0≤NK<⋯<N2<N1 ≤1000.
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
题意
- 两个多项式相乘,并进行格式化输出
- 这道题和1002题的多项式相加很像,保留一位小数输出就行
解题思路
- 将两个多项式存到数组里,然后相乘,这里很容易就想到双重for循环实现
- 每一项的指数就可以作为数组中的索引,然后存储对应项的系数
- 我看网上很多人说用Java写这道题有一个测试点不会通过,我也不知道是哪个
代码实现
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
/**
* @Author: 胡奇夫
* @QQ: 1579328766
* @CreateTime: 2020-05-11-22-19
* @Descirption: Pat甲级1009
*/
public class Testnine {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
double[] list1 = new double[1001];//第一行输入
double[] list2 = new double[1001];//第二行输入
double[] list3 = new double[2002];//运算后的数组
int sum = 0;//运算后的多项式的非零项个数
String[] strlist = br.readLine().split(" ");
for(int i = 1;i<strlist.length-1;i+=2)
{
list1[Integer.parseInt(strlist[i])] = Double.parseDouble(strlist[i+1]);
}
strlist = br.readLine().split(" ");
for(int i = 1;i<strlist.length-1;i+=2)
{
list2[Integer.parseInt(strlist[i])] = Double.parseDouble(strlist[i+1]);
}
//进行多项式相乘,并将结果存储到list3里
for(int i = 0;i<list1.length;i++)
{
if(list1[i]!=0.0)
{
for(int j = 0;j<list2.length;j++)
{
if(list2[j]!=0.0)
{
list3[i+j] += list1[i]*list2[j];
}
}
}
}
//计算运算后的多项式中非零项的个数
for(int i = 0;i<list3.length;i++)
{
if(list3[i]!=0.0) sum++;
}
System.out.print(sum);
//格式化输出
for(int i = list3.length-1;i>=0;i--)
{
if(list3[i]!=0.0)
{
System.out.print(" "+i+" ");
System.out.printf("%.1f",list3[i]);
}
}
System.out.println();
}
}