1009 Product of Polynomials

题目

题意：给两个表达式，算他们的积 

#include<iostream>
#include<queue>
#include<cmath>
#include<algorithm>
using namespace std;
struct ss {
	int exp;
	double coef;
};
bool cmp(struct ss a,struct ss b) {
	return a.exp>b.exp;
}
int main() {
	int n,m;
	cin>>n;
	struct ss polyA[n];
	for(int i=0; i<n; ++i)
		cin>>polyA[i].exp>>polyA[i].coef;
	cin>>m;
	struct ss ans[n*m];
	double exp,coef;
	int k=0;
	for(int i=0; i<m; ++i) {
		cin>>exp>>coef;
		for(int j=0; j<n; ++j) {//多项式运算
			ans[k].exp=exp+polyA[j].exp;
			ans[k++].coef=coef*polyA[j].coef;
		}
	}
	sort(ans,ans+k,cmp);
	queue<struct ss> s;
	vector<struct ss> ans1;
	s.push(ans[0]);
	int flag=0;
	for(int i=1; i<k; ++i) {
		if(s.front().exp==ans[i].exp)//合并多项式
			s.front().coef+=ans[i].coef;
		else {
			if(fabs(s.front().coef)>0.05)//坑：非零项才算数
			ans1.push_back(s.front());
			s.pop();
			s.push(ans[i]);
		}
	}
	if(!s.empty())
	{
		ans1.push_back(s.front());
			s.pop(); 
	}
	cout<<ans1.size();
	for(int i=0; i<ans1.size(); ++i)
		printf(" %d %.1lf",ans1[i].exp,ans1[i].coef);
	return 0;
}