PAT甲级 1002 A+B for Polynomials

#include<bits/stdc++.h>
using namespace std;
int k,n,sum,cnt=1;
double a;
double ans[1010];
map<int,double,greater<int> > ma;
int main(){
    cin>>k;
    for(int i=0;i<k;i++){
        cin>>n>>a;
        ma[n]=a;
    }
    cin>>k;
    
    for(int i=0;i<k;i++){
        cin>>n>>a;
        ma[n]=ma[n]+a;
    }

    for (map<int, double>::iterator it = ma.begin(); it != ma.end(); it++) {
        if(it->second ==0) continue;
        else{
            ans[cnt++]=it->first;
            ans[cnt++]=it->second;
        }
    }
    if(cnt==1) {
        cout<<0;
        return 0;
    } 
    cout<<cnt/2;
    for(int i=1;i<cnt;i+=2){
        printf(" %.0lf %.1lf",ans[i],ans[i+1]);
    }
    return 0;
}