#include #include #include /** * See & Say Sequence * @Author: Ace * Bugs: None known * @Version: * 0.0.0.0 - Algorithm determined * 0.0.0.1 - compute_line complete, testing/debugging * 0.0.0.2 - Minor corrections, driver complete. * 0.0.0.3 - Release * 0.0.0.4 - Exception handler done, added more comments */ /** * Find nth term by generating * all terms from the 2nd to * n-1. Every term generated * uses the previous term */ std::string compute_line(std::string curr) { std::ostringstream next; char last(curr[0]); unsigned short count(0); for (std::string::iterator it = curr.begin(); it < curr.end(); it++) { //are there more numbers to add? if (last == *it) { //if no, just prepare for next count += 1; }else{ //add the new value and the old string next << count; next << last; count = 1; } //get the last char in the string last = *it; // now print the last item if (it != curr.end() && it == --curr.end()) { next << count; next << *it; } } return next.str(); } int main() { std::string line = "1"; unsigned short count; std::cout << "How many lines to print: "; try { std::cin >> count; if(std::cin.fail() || std::cin.bad()) throw 'n'; std::cout << std::endl; for (unsigned short i = 0; i < count; i++) { std::cout << line << std::endl; line = compute_line(line); } }catch(char ex) { std::cout << std::endl; switch(ex) { case 'n': std::cout << "Error! Usage: "; break; default: std::cout << "Unknown error"; break; } } return 0; }

See&Say