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<iostream>
#include<cstdio>
#include<string.h>

using namespace std;
double a[1001] = { 0.0 };
char str[1000] = "" , str1[100];//将str[100]扩大为1000，运行时错误便可以去掉
int main() {
    int n;
    cin >> n;
    int i;
    double j;
    while (n--) {
        cin >> i >> j;
        a[i] += j;
    }
    cin >> n;
    while (n--) {
        cin >> i >> j;
        a[i] += j;
    }
    int cnt = 0;
    for (i = 1000; i >= 0; i--) {
        if (a[i] != 0) {
            sprintf(str1, " %d %0.1lf", i, a[i]);
            strcat(str, str1);
            cnt++;
        }
    }
    cout << cnt << str;
    return 0;
}