C++ 代码

#include <iostream>
#include <vector>
#include <string>
#include <unordered_map>

using std::cout;
using std::endl;
using std::cin;
using std::string;
using std::unordered_map;
using std::vector;

int main()
{
    string str;
    unordered_map<char, vector<int>> Map;
    vector<char> vec;

    cin >> str;

    if (str.empty()) {
        cout << "Empty input!" << endl;
        return 0;
    }

    int len = str.length();
    for (int i = 0; i < len; i++) {
        if (Map[str[i]].size() == 0)
            vec.push_back(str[i]);
        Map[str[i]].push_back(i);
    }

    // 输出结果
    for (auto elem : vec) {
        string res;
        for (size_t i = 0; i < Map[elem].size(); i++) {
            res += elem;
            res += ':';
            res += std::to_string(Map[elem][i]);
            if (i < Map[elem].size() - 1) { //省去最后一个逗号
                res += ',';
            }
        }
        res += '\n';
        if(Map[elem].size() == 1)
            continue;
        cout << res;
    }

    return 0;
}