题解 | 合并表记录

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

int main() {
    map<int, int> dict;

    int count, a, b;

    cin >> count;


    while (cin >> a >> b && count--) {

        if (dict.find(a) != dict.end()) {
            dict[a] = b + dict[a];

        } else {
            dict[a] = b;
        }

        if (!count)
            break;
    }

    vector<int> keys;
    keys.reserve(dict.size());

// 遍历 dict 获取 key
    for (const auto& pair : dict) {
        keys.push_back(pair.first);
    }

    sort(keys.begin(), keys.end());

    for (int key : keys) {
        cout << key << " " << dict[key] << endl;
    }
}
// 64 位输出请用 printf("%lld")