PAT(Advanced)甲级---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

 

代码：

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<map>
#include<cmath>
using namespace std;

map<int, double> m;

int main(){
    int K;
    int index = 2;
    while (index-- > 0){
        scanf("%d", &K);
        int exp;
        double cof;
        for (int i = 0; i < K; i++){
            scanf("%d%lf", &exp, &cof);
            m[exp] += cof;
        }
    }
    int sz = 0;
    for (auto it = m.begin(); it != m.end(); it++) if (it->second != 0)sz++;
    printf("%d", sz);
    for (auto it = m.rbegin(); it != m.rend(); it++){
        if(it->second!=0)printf(" %d %.1lf", it->first, it->second);
    }
}

 

总结：

• 注意系数为0的情况