PATA1009_模拟（难度：⭐️⭐️）

难在有几个单词不认识，要靠测试用例猜。

---

#include <bits/stdc++.h>
using namespace std;
struct node {
    int e;
    double a;
};
vector<node> v, ans;
map<int, double> mp;
int main () {
    int k, e;
    double a;
    scanf ("%d", &k);
    for (int i = 0; i < k; i++) {
        scanf ("%d %lf", &e, &a);
        v.push_back(node{e, a});
    }
    scanf ("%d", &k);
    for (int i = 0; i < k; i++) {
        scanf ("%d %lf", &e, &a);
        for (auto it : v) mp[it.e + e] += a * it.a;
    }
    for (auto it : mp) 
        if (it.second != 0.0) ans.push_back(node{it.first, it.second});
    cout << ans.size();
    for (int i = ans.size() - 1; i >= 0; i--)
        printf (" %d %.1lf", ans[i].e, ans[i].a);
}