1009 Product of Polynomials (25)

题目信息

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

代码

#include<iostream>
using namespace std;
int main(){
    int k1,k2,ex,cnt=0;
    scanf("%d",&k1);
    double co,a[2002]={0},ans[2002]={0};
    for(int i=0;i<k1;i++){
        scanf("%d",&ex);
        scanf("%lf",&a[ex]);
    }
    scanf("%d",&k2);
    for(int i=0;i<k2;i++){
        scanf("%d %lf",&ex,&co);
        for(int j=2001;j>=0;j--){
            if(a[j]!=0){
                ans[j+ex]+=a[j]*co;
            }
        }
    }
    for(int i=0;i<2002;i++){
        if(ans[i]!=0) cnt++;
    }
    cout<<cnt;
    for(int i=2001;i>=0;i--){
        if(ans[i]!=0) printf(" %d %.1f",i,ans[i]);
    }
    return 0;
}

测试结果