PAT 1002. A+B for Polynomials (25)

题目地址： http://www.patest.cn/contests/pat-a-practise/1002

这个题我能说我交了无数次吗？ 坑， 系数是0 不能输出

#include<iostream>
#include<iomanip>
#include<map>

using namespace std;

const double eps = 1e-9;
int main() {
        int k;
        while(cin >> k) {
                map<int, double> p;
                int e; 
                double a;
                for (int i = 0; i < k; ++i) {
                        cin >> e >> a;
                        p[e] = a;
                }
                cin >> k;
                for (int i = 0; i < k; ++i) {
                        cin >> e >> a;
                        if (p.count(e)) {
                                double x = p[e];
                                if (!(x + a > -eps && x + a < eps)) {
                                        p[e] += a;
                                } else {
                                        p.erase(e);
                                }
                        } else {
                                p[e] = a;
                        }
                }
                cout << p.size();
                for (map<int, double>::reverse_iterator iter = p.rbegin(); iter != p.rend(); ++iter) {
                        cout << " " << iter->first << " ";
                        cout << fixed << setprecision(1) << iter->second; 
                }
        }
        return 0;
}