1009 Product of Polynomials

1009 Product of Polynomials (25 分)

This time, you are supposed to find A×B where A and B are two polynomials.

Input Specification:

Each input file contains one test case. Each case occupies 2 lines, and each line contains the information of a polynomial:

K N​1​​ a​N​1​​​​ N​2​​ a​N​2​​​​ ... N​K​​ a​N​K​​​​

where K is the number of nonzero terms in the polynomial, N​i​​ and a​N​i​​​​ (i=1,2,⋯,K) are the exponents and coefficients, respectively. It is given that 1≤K≤10, 0≤N​K​​<⋯

Output Specification:

For each test case you should output the product of A and B in one line, with the same format as the input. Notice that there must be NO extra space at the end of each line. Please be accurate up to 1 decimal place.

Sample Input:

2 1 2.4 0 3.2
2 2 1.5 1 0.5

Sample Output:

3 3 3.6 2 6.0 1 1.6


题型分类:模拟、数学运算

题目大意:计算两个多项式的乘积

解题思路:使用STL模板里面的map,指数相加,系数相乘。需要注意的是,最后输出polyResult时,要判断系数是否为0,系数为0的项不计入输出项内。


#include 
#include 

using namespace std;

const int maxn = 1010;

map poly, polyResult;

int main(int argc, char** argv) {
	int K1, K2, expo;
	double coef;
	scanf("%d", &K1);
	while(K1--){
		scanf("%d %lf", &expo, &coef);
		poly[expo] = coef;
	}
	scanf("%d", &K2);
	while(K2--){
		scanf("%d %lf", &expo, &coef);
		for(map::iterator it = poly.begin(); it != poly.end(); it++){
			polyResult[expo + it->first] += coef * it->second; 
		}
	}
	int cnt = 0;
	for(map::iterator it = polyResult.begin(); it != polyResult.end(); it++){
		if(it->second != 0.0) cnt++;
	}
	printf("%d", cnt);
	for(map::reverse_iterator it = polyResult.rbegin(); it != polyResult.rend(); it++){
		if(it->second != 0.0) printf(" %d %.1f", it->first, it->second);
	}
	return 0;
}

 

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