PAT 1002 A+B for Polynomials

1002 A+B for 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​​​​ (,) 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

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;


int main(){
    map<int,double> mp;
    map<int,double>::iterator it;

    int n;
    cin >> n;
    while(n--){
        int x;double y;
        cin >> x >> y;
        mp[x]+=y;
    }
    cin >> n;
    while(n--){
        int x;double y;
        cin >> x >> y;
        mp[x]+=y;
    }
    vector<pair<int,double>> vec;
    for(it=mp.begin();it!=mp.end();it++){
//        cout << it->first << " " << it->second << " ";
        if(it->second != 0) {
            vec.push_back(make_pair(it->first, it->second));
        }
    }
    cout << vec.size();
    for(int i=vec.size()-1;i >= 0;i--){
//        cout << vec[i].first << " " << fixed << setprecision(1)<< vec[i].second;
        printf(" %d %.1f",vec[i].first,vec[i].second);

    }

    return 0;
}

——map  make_pair vector 之间的骚操作。。