PAT (Advanced Level) Practice 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 $a{}_{N_i}$ (i=1,2,⋯,K) are the exponents and coefficients, respectively. It is given that 1≤K≤10，0≤$N_K$​​ <⋯<$N_{}2$ <​$N_1$​​ ≤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

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

double A[1005], B[1005];
int main() {
    int K1, K2;
    cin >> K1;
    for (int i = 0; i < K1; i++){
        int n;
        double a;
        cin >> n >> a;
        A[n]= a;
    }
    cin >> K2;
    for (int i = 0; i < K2; i++){
        int n;
        double a;
        cin >> n >> a;
        B[n] = a;
    }
    int ans = 0;
    for (int i = 0; i <= 1000; i++){
        A[i] += B[i];
        if (A[i] != 0) ans++;
    }
    cout << ans ;
    for (int i = 1000; i >= 0; i--){
        if (A[i] != 0)printf(" %d %.1lf",i,  A[i]);
    }
    cout <<"\n";
    return 0;
}