1009 Product of Polynomials (25分)

#include <iostream>

using namespace std;
double poly1[1001];
double poly2[1001];
double multiply[2002];
int main(){
    
    int n1, n2;
    int index;
    int count = 0;
    cin >> n1;
    for(int i=0; i<n1; i++){
    
        cin >> index;
        cin >> poly1[index]; 
    }
    cin >> n2;
    for(int i=0; i<n2; i++){
    
        cin >> index;
        cin >> poly2[index]; 
    }
    for(int i=0; i<1001; i++){
    
        if(poly1[i] != 0){
    
            for(int j=0; j<1001; j++){
    
                if(poly2[j] != 0){
    
                    multiply[i+j] += poly1[i] * poly2[j];
                }
            }
        }
    }
    for(int i=2002; i >= 0 ; i--){
    
        if(multiply[i] != 0)
            count++;
    }
    cout << count;
    for(int i=2002; i >= 0 ; i--){
    
        if(multiply[i] != 0)
            printf(" %d %.1lf", i, multiply[i]);
    }


    return 0;
}