设计函数分别求两个一元多项式的乘积与和。

输入格式:

输入分2行，每行分别先给出多项式非零项的个数，再以指数递降方式输入一个多项式非零项系数和指数（绝对值均为不超过1000的整数）。数字间以空格分隔。

输出格式:

输出分2行，分别以指数递降方式输出乘积多项式以及和多项式非零项的系数和指数。数字间以空格分隔，但结尾不能有多余空格。零多项式应输出0 0。

#include <iostream>
#include <vector>
#include <algorithm>
#include <list>
using namespace std;
class MyCompare
{
public:
    bool operator()(pair<int, int> p1, pair<int, int> p2)
    {
        if (p1.first > p2.first)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
};

int main()
{
    vector<pair<int, int>> v1;
    vector<pair<int, int>> v2;
    vector<pair<int, int>> v3;// 和
    vector<pair<int, int>> v4;// 积
    
    int number_of_terms = 0;
    scanf("%d", &number_of_terms);
    while (number_of_terms != 0)
    {
        int coefficient = 0;
        int index = 0;
        scanf("%d", &coefficient);
        scanf("%d", &index);
        number_of_terms--;
        v1.push_back(pair<int, int>(index, coefficient));
    }

    scanf("%d", &number_of_terms);
    while (number_of_terms != 0)
    {
        int coefficient = 0;
        int index = 0;
        scanf("%d", &coefficient);
        scanf("%d", &index);
        number_of_terms--;
        v2.push_back(pair<int, int>(index, coefficient));
    }

    // 求积
    for (int i = 0; i < v1.size(); i++)
    {
        for (int j = 0; j < v2.size(); j++)
        {
            v4.push_back(pair<int, int>(v1[i].first+v2[j].first, v1[i].second*v2[j].second));
        }
    }
    
    sort(v4.begin(), v4.end(), MyCompare());
    list<pair<int, int>> tmp(v4.begin(), v4.end());
    auto cur = tmp.begin();
    cur++;
    auto prev = tmp.begin();
    while (cur != tmp.end())
    {
        if (cur->first == prev->first)
        {
            prev->second = prev->second + cur->second;
            cur = tmp.erase(cur);
        }
        else
        {
            prev++;
            cur++;
        }
    }

    cur = tmp.begin();
    while(cur != tmp.end())
    {
        if (cur->second == 0)
        {
            cur = tmp.erase(cur);
        }
        else{
            cur++;
        }
    }

    if (tmp.empty())
    {
        tmp.push_back(pair<int,int>(0,0));
    }
    cur = tmp.begin();
    int y = 0;
    int size = tmp.size();
    while (cur != tmp.end())
    {
        if (y != size - 1)
        {
            cout << cur->second << ' ' << cur->first << ' ';
            cur++;
            y++;
        }
        else
        {
            cout << cur->second << ' ' << cur->first;
            cout << endl;
            cur++;
            y++;
        }
    }
    
    // 求和
    int i = 0;
    int j = 0;
    while (i < v1.size() && j < v2.size())
    {
        if (v1[i].first > v2[j].first)
        {
            v3.push_back(v1[i]);
            i++;
        }
        else if (v1[i].first < v2[j].first)
        {
            v3.push_back(v2[j]);
            j++;
        }
        else
        {
            v3.push_back(pair<int, int>(v1[i].first, v1[i].second + v2[j].second));
            i++;
            j++;
        }
    }
    
    if (i == v1.size())
    {
        while (j < v2.size())
        {
            v3.push_back(v2[j]);
            j++;
        }
    }
    
    if (j == v2.size())
    {
        while (i < v1.size())
        {
            v3.push_back(v1[i]);
            i++;
        }
    }

    list<pair<int, int>> tmp2(v3.begin(), v3.end());
    auto cur2 = tmp2.begin();
    while(cur2 != tmp2.end())
    {
        if (cur2->second == 0)
        {
            cur2 = tmp2.erase(cur2);
        }
        else{
            cur2++;
        }
    }
    if (tmp2.empty())
    {
        tmp2.push_back(pair<int,int>(0,0));
    }

    cur2 = tmp2.begin();
    y = 0;
    size = tmp2.size();
    while (cur2 != tmp2.end())
    {
        if (y != size - 1)
        {
            cout << cur2->second << ' ' << cur2->first << ' ';
            cur2++;
            y++;
        }
        else
        {
            cout << cur2->second << ' ' << cur2->first;
            
            cur2++;
            y++;
        }
    }

    return 0;
}