202504231438 1002 A+B for Polynomials

1002 A+B for Polynomials - PAT (Advanced Level) Practice

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 $a_{N_i}$​​ ($i=1,2,\cdots ,K$) are the exponents and coefficients, respectively. It is given that $1\le K\le 10，0\le N_K<\cdots <N_2<N_1\le 1000$.

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

solve

模拟多项式相加，使用 map 来记录指数和系数的联系，然后相同指数的系数相加，注意当系数为0时即相加抵消，该项消除。

#include<iostream>
#include<map>
#include<algorithm>
using namespace std;
map<int, double, greater<int>> m;
 
int main() {
    int k;
    for(int i = 0; i < 2; i++) {
        cin >> k;
        while(k--) {
            int n;
            double a;
            cin >> n >> a;
            m[n] += a;
            if(m[n] == 0) 
                m.erase(n);
        }
    }
    cout << m.size();
    for_each(m.begin(),m.end(), [](const auto &pair) {
        printf(" %d %.1f", pair.first, pair.second);
    });
    cout << endl;
 
    return 0;
}