/* Instructions for use: enter a string to check: e.g abycbaxbckgm enter a number of unique elements to scan for e.g 3 example input abycbaxbckgm 3 */ #include #include #include /* // functor for find_if _ replaced with lambda expression struct isEqual { isEqual(char lettr) : letter(lettr) {} bool operator() (const std::pair& check ) { return letter == check.first; } char letter; }; */ int main() { std::string input; int numUnique {0}; std::cin >> input; std::vector> charCount; // count instances for(auto letter : input) { // check to see if letter exists in charCount //functor predicate method // auto iter = std::find_if(charCount.begin(), charCount.end(),isEqual(letter)); //lambda predicate method // http://en.cppreference.com/w/cpp/language/lambda // [capture] (parameters) {body} auto iter = std::find_if(charCount.begin(), charCount.end(),[&letter](const std::pair <r){return ltr.first == letter;}); if(iter == charCount.end()) { // "Letter not found, insert count" charCount.push_back(std::pair(letter, 1)); } else { //letter found, increase count iter->second = ++(iter->second); } } std::cout << "all data (and counts)\n"; // print charCount index and total count for(auto& pair : charCount) { std::cout << pair.first << " " << pair.second << std::endl; } //find and print all elements with count of 1 in map - hacky, but it works :) std::cin >> numUnique; std::cout << "Finding first " << numUnique << " unique elements" << std::endl; int i{1}; auto iter = charCount.begin(); while(i <= numUnique) { while(iter != charCount.end()) { if(iter->second == 1) { std::cout << i << " " << iter->first << std::endl; ++iter; ++i; break; } ++iter; } if(iter == charCount.end()) { std::cout << i << " null" << std::endl; ++i; } } return 0; }

NonRepeatingChar