PAT 1009 Product of Polynomials (25分)

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Question: Calculate A multiplied by B, where A and B are two polynomials.

Idea: Multiply polynomials, use $A$ each multiplied to$For$ each item of$B$ , the coefficients are multiplied and the exponents are added.

As shown in the following table, one-dimensional arrays can be used to store polynomials.

Example 2 1 2.4 0 3.2 can be expressed as $2.4x+.\; 3.2$ , which is stored in the array as follows:

Example 2 2 1.5 1 0.5 can be expressed as $1.5x^2+0..\; 5X$ , which is stored in the array as follows:

The result of multiplying the two is $3.6x^3+6.0x^2+.\; 1..\; 6X$ , which is stored in the array as follows:

AC code:

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;

double a[1010], b[1010], c[2010];

int main()
{
    
    
    int n, exp, aexp = -1, bexp = -1;
    double coe;
    
    scanf("%d", &n);
    for(int i = 0; i < n; i++)
    {
    
    
        scanf("%d%lf", &exp, &coe);
        aexp = max(aexp, exp);
        a[exp] = coe;
    }
    
    scanf("%d", &n);
    for(int i = 0; i < n; i++)
    {
    
    
        scanf("%d%lf", &exp, &coe);
        bexp = max(bexp, exp);
        b[exp] = coe;
    }
    
    for(int i = 0; i <= aexp; i++)
        for(int j = 0; j <= bexp; j++)
            c[i + j] += a[i] * b[j];
    
    int ans = 0;
    for(int i = aexp + bexp; i >= 0; i--)   ans += (c[i] != 0);
    printf("%d", ans);
    
    for(int i = aexp + bexp; i >= 0; i--)
        if(c[i] != 0)
            printf(" %d %.1f", i, c[i]);
    
    return 0;
}

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