PAT (Advanced Level) 1002. A+B for Polynomials (25)

#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<cstdio>
using namespace std;

double a[1500],b[1500];
int k;

int main()
{
for(int i=0;i<=1000;i++) a[i]=b[i]=0;
int Max=-1;
scanf("%d",&k);
for(int i=1;i<=k;i++)
{
int id;double num;
scanf("%d%lf",&id,&num);
Max=max(Max,id);
a[id]=num;
}

scanf("%d",&k);
for(int i=1;i<=k;i++)
{
int id;double num;
scanf("%d%lf",&id,&num);
Max=max(Max,id);
b[id]=num;
}

int cnt=0;
for(int i=Max;i>=0;i--)
if(a[i]+b[i]!=0) cnt++;

printf("%d",cnt);
int op=0;
for(int i=Max;i>=0;i--)
{
if(a[i]+b[i]!=0){
printf(" %d %.1lf",i,a[i]+b[i]);
}
}
return 0;
}