HJ8 合并表记录 HJ08

​​HJ8合并表记录​​

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

int main(int argc, char *argv[]) {
    int k, v;
    int n = 0;
    std::map<int, int> m;
    
    cin >> n;
    while (n-- > 0) {
        cin >> k;
        cin >> v;
        if (m.find(k) == m.end()) {
            m[k] = v;
        } else {
            m[k] += v;
        }
    }
    for (auto it = m.begin(); it != m.end(); ++it) {
        std::cout << it->first << " " << it->second << "\n";
    }
    return 0;
}

实际读取数据一般是从文件， 用std::ifstream,  需要引入fstream头文件 #include <fstream>

 main.cpp

#include <iostream>
#include <fstream>
#include <sstream>
#include <map>

class HJ08 {
public:
    static std::string file_get_contents(const std::basic_string<char>& path) {
        std::ifstream file;
        file.open(path, std::ios_base::in);
        if (!file.is_open()) {
            std::cout << "打开\"" << path << "\"失败";
            return "";
        }
        std::stringstream s;
        s << file.rdbuf();
        file.close();
        return s.str();
    }

    static std::map<int, int> mergedPairs(const std::basic_string<char>& path) {
        std::map<int, int> m;
        std::ifstream ifs;

        ifs.open(path, std::ios_base::in);
        if (!ifs.is_open()) {
            std::cout << "打开\"" << path << "\"失败";
            return m;
        }
        int n = 0;
        ifs >> n;

        int k, v;
        while (n-- > 0) {
            ifs >> k;
            ifs >> v;
            if (m.find(k) == m.end()) {
                m[k] = v;
            } else {
                m[k] += v;
            }
        }
        ifs.close();
        return m;
    }
};

int main() {
    // std::string content = HJ08::file_get_contents("../input_01.txt");
    // std::cout << content;
    std::map<int, int> m;
    m = HJ08::mergedPairs("../input_01.txt");

    // std::map<int, int>::const_iterator
    for (auto it = m.begin(); it != m.end(); ++it) {
        std::cout << it->first << " " << it->second << "\n";
    }
//    for (auto &pair : m) {
//        std::cout << pair.first << " " << pair.second << "\n";
//    }

    return 0;
}

        pair<int, int>i;
        cin >> i.first >> i.second;
        m[i.first] += i.second;