浙江大学PAT上机题解析之1009. Product of Polynomials (25)

1009. Product of Polynomials (25)

时间限制 

400 ms

内存限制 

32000 kB

代码长度限制 

16000 B

判题程序   

Standard

作者   

CHEN, Yue

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 N1 a_N1 N2 a_N2 ... NK a_NK, where K is the number of nonzero terms in the polynomial, Ni and a_Ni (i=1, 2, ..., K) are the exponents and coefficients, respectively.  It is given that 1 <= K <= 10, 0 <= NK < ... < N2 < N1 <=1000. 

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

#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>


using namespace std;
typedef struct Node
{
  int exp;//指数
  float coe;//系数
}Node;

Node product(Node a,Node b)
{
  a.exp = a.exp+b.exp;
  a.coe = a.coe*b.coe;
  return a;
}
bool compare(Node a,Node b)
{
    return a.exp>b.exp;
}

int main()
{
  Node node;
  int M,N;
  
  vector<Node>  vec1,vec2,vec,vec3;
  vector<Node>::iterator it1,it2;

  cin>>M;
  while(M--)
  {
    cin>>node.exp>>node.coe;
    vec1.push_back(node);
  }
  cin>>N;
  while(N--)
  {
    cin>>node.exp>>node.coe;
    vec2.push_back(node);
  }
  for (it1=vec1.begin();it1!=vec1.end();it1++)
  for (it2=vec2.begin();it2!=vec2.end();it2++)
    {
      Node  t = product(*it1,*it2);
      if (t.coe !=0)
            vec.push_back(t);    
      }
    sort(vec.begin(),vec.end(),compare);
  for (it1=vec.begin();it1!=vec.end();it1 =it2)
    {  
    for (it2=it1+1;it2!=vec.end() && ((*it1).exp == (*it2).exp);it2++)
           (*it1).coe +=(*it2).coe;
    if ((*it1).coe !=0)
    {
      vec3.push_back(*it1);
    }
  }
 cout<<vec3.size(); 
 for (it1=vec3.begin();it1!=vec3.end();it1++)  
   cout<<" "<<(*it1).exp<<" "<<fixed<<setprecision(1)<<(*it1).coe; 
 cout<<endl;  


 //   system("pause");
  return 0;
}