1009. Product of Polynomials (25)

数组模拟多项式乘法

#include<iostream>
#include<vector>
#include<algorithm>
typedef struct Node
{
	double sum;
	int e;
}Node;
#define MAX 3000
int main()
{
	int n1, n2;
	while(scanf("%d",&n1)!=EOF)
	{
		std::vector<Node> a(n1);
		for(int i = 0; i < n1; ++i)
			scanf("%d %lf\n", &a[i].e, &a[i].sum);
		scanf("%d",&n2);
		std::vector<Node> b(n2);
		for(int i = 0;i < n2; ++i)
			scanf("%d %lf",&b[i].e, &b[i].sum);
		//product
		std::vector<double> p;
		p.assign(MAX+1, 0.0);
		for(int i = 0; i < n1; ++i)
		{
			for(int j = 0; j < n2; ++j)
			{
				Node tmp;
				tmp.e = a[i].e+b[j].e;
				tmp.sum = a[i].sum*b[j].sum;
				p[tmp.e] += tmp.sum;
			}
		}
		//output
		int cnt = 0;
		for(int i = MAX; i >= 0; --i)
		{
			if(std::fabs(p[i]) > 1e-6)
				cnt++;
		}
		printf("%d", cnt);
		for(int i = MAX; i >= 0; --i)
		{
			if(std::fabs(p[i]) > 1e-6)
				printf(" %d %.1lf", i, p[i]);
		}
		printf("\n");
	}
	return 0;
}