random_cpp_algorithms.cpp

#include <iostream>
#include <iterator>
#include <algorithm>
#include <string>
#include <unordered_map>

template<typename InputIterator, typename T, typename Functor>
void split(InputIterator first, InputIterator last, const T& t, Functor f)
{
    while(true)
    {
        InputIterator found = std::find(first, last, t);
        f(first, found);
        if(found == last)
        {
            break;
        }
        first = ++found;
    }
}

template<typename Container, typename T = typename Container::value_type>
Container find_unique(const Container &container) 
{
    std::unordered_map<T, int> histogram;
    Container output;
    for(const auto &value: container)
    {
        ++histogram[value];
    }
    std::copy_if(container.begin(), container.end(), std::back_inserter(output), [&](const auto& value) -> bool 
    {
        return histogram[value] == 1;
    });
    return output;
}

template<typename Container, typename Functor>
Container keep_if(const Container &container, Functor f)
{
    Container output;
    std::copy_if(container.begin(), container.end(), std::back_inserter(output), f);
    return output;
}

int main()
{
    std::vector<int> values {1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 6, 7, 9, 9, 10, 10, 11, 14, 16};
    auto uniques = find_unique(values);
    std::cout << "Found " << uniques.size() << " unique items." << std::endl;
    for(auto item: uniques)
    {
        std::cout << "Found unique item: " << item << std::endl;
    }
    
    std::string test("hello,split,by,string");
    split(test.begin(), test.end(), ',', [](std::basic_string<char>::iterator begin, std::basic_string<char>::iterator end)
    {
        std::string output(begin, end);
        std::cout << output << std::endl;
    });
    
    auto ones = keep_if(values, [](int value) { return value == 1;});
    std::cout << "There are " << ones.size() << " ones" << std::endl;
    return 0;
}