题解 | #合并表记录#

#include <iostream>
#include <unordered_map>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int n;
    unordered_map<int, int> res;
    cin >> n;
    while (n--) {
        int n1, n2;
        cin >> n1 >> n2;
        if (res.find(n1) != res.end())
            res[n1] += n2;
        else
            res[n1] = n2;
    }
    std::vector<std::pair<int, int>> tmp;
    for (auto& i : res)
        tmp.push_back(i);
    std::sort(tmp.begin(), tmp.end(), [ = ](std::pair<int, int>& a, std::pair<int, int>& b) {
        return a.first < b.first;
    });
    for (auto iter = tmp.begin(); iter != tmp.end(); ++iter) {
        cout << iter->first << " " << iter->second << endl;
    }
    return 0;
}