PAT-甲级-1002 A+B for Polynomials C++

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:

$K$ N1​ aN1​​ N2​ aN2​​ ... NK​ aNK​​

where $K$ is the number of nonzero terms in the polynomial, Ni​ and aNi​​ ($i=1,2,\cdots ,K$) are the exponents and coefficients, respectively. It is given that $1\le K\le 10$，0≤NK​<⋯<N2​<N1​≤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

题意：

题目意思是计算两个多项式的加法。

分析：

水题。用水桶法，用数组下标表示指数，数组值表示系数，逆序输出，值为0则不输出。

代码：

//
// Created by yaodong on 2023/7/5.
//
#include "iostream"
#include "cstring"
int main() {
    double num[1001];
    memset(num, 0, sizeof(num));
    int k, exp;
    double coe;
    std::cin >> k;
    for (int i = 0; i < k; ++i) {
        std::cin >> exp >> coe;
        num[exp] += coe;
    }
    std::cin >> k;
    for (int i = 0; i < k; ++i) {
        std::cin >> exp >> coe;
        num[exp] += coe;
    }
    int len = 0;
    for (int i = 0; i < 1001; ++i) {
        if(num[i] != 0)
            len++;
    }
    std::cout << len;
    for (int i = 1000; i >= 0; --i) {
        if(num[i] != 0)
            printf(" %d %.1f", i, num[i]);
    }
}