pat 1009 Product of Polynomials

#include<stdio.h>
#include<vector>
#include<string.h>
using namespace std;
struct element{
    int n;
    float an;
};
float result[2000];
int main(){
    int k1, k2,num=0;
    memset(result, 0, sizeof result);
    scanf("%d", &k1);
    vector<element>v1(k1);
    for (int i = 0; i < k1; i++){
        scanf("%d %f", &v1[i].n, &v1[i].an);
    }
    scanf("%d", &k2);
    vector<element>v2(k2);
    for (int i = 0; i < k2; i++){
        scanf("%d %f", &v2[i].n, &v2[i].an);
        for (int j = 0; j < k1; j++){
            int a=v2[i].n + v1[j].n;
            result[a] += v2[i].an*v1[j].an;
        }
    }
    for (int i = v1[0].n + v2[0].n; i >= 0; i--){
        if (result[i] != 0)num++;
    }
    printf("%d", num);
    for (int i = v1[0].n + v2[0].n; i >= 0; i--){
        if (result[i] != 0){
            printf(" %d %.1f",i, result[i]);
        }
    }
    printf("\n");
    return 0;
}