PAT甲级——A1002 A+B for Polynomials

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​​​​ (,) are the exponents and coefficients, respectively. It is given that 1，0.

Output Specification:

For each test case you should output the sum 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 to 1 decimal place.

Sample Input:

2 1 2.4 0 3.2
2 2 1.5 1 0.5

Sample Output:

3 2 1.5 1 2.9 0 3.2

使用map进行映射即可，但需注意输出格式

#include <iostream>
//#include <vector>
#include <map>
#include <stack>
using namespace std;

int main()
{
    map<double, double,greater<double>>data;//从大到小排序
    for (int i = 0; i < 2; ++i)//输入两组数据
    {
        int k;
        cin >> k;
        for (int j = 0; j < k; ++j)//接受每组数据
        {
            double a, b;
            cin >> a >> b;
            data[a] += b;
            if (data[a] == 0)//系数为0则删除
                data.erase(a);
        }
    }
    cout << data.size();
    for (auto ptr = data.begin(); ptr != data.end(); ++ptr)
    {
        cout << " " << ptr->first << " ";
        printf("%.1f", ptr->second);
    }
    return 0;
}