PAT (Advanced Level) 1002 A+B for Polynomials

题意

给定两个多项式A、B，计算A+B。

思路

搞个map记录一下对应指数下的系数即可。

• 坑点：
• 系数和为0需要被舍弃。

代码

#include <bits/stdc++.h>
using namespace std;
int main() {
	map<int, double> mp;
	auto read = [&] {
		int n;
		scanf("%d", &n);
		for (int i = 0; i < n; ++i) {
			int nk;
			double ank;
			scanf("%d%lf", &nk, &ank);
			mp[nk] += ank;
		}
	};
	read();
	read();
	for (auto it = mp.begin(); it != mp.end(); ++it) 
	 	if (it->second == 0) mp.erase(it);
	int num = mp.size();
	printf("%d", num);
	for (auto it = mp.rbegin(); it != mp.rend(); ++it) {
		printf(" %d %.1lf", it->first, it->second);
	}
	printf("\n");
	return 0;
}

HINT

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