cw_printer_errors.cc

// Codewars: Printer Errors
// 7 kyu

// URL: https://www.codewars.com/kata/56541980fa08ab47a0000040/train/cpp

// In a factory a printer prints labels for boxes. For one kind of boxes the printer has to use colors which, 
// for the sake of simplicity, are named with letters from a to m.

// The colors used by the printer are recorded in a control string. For example a "good" control string would 
// be aaabbbbhaijjjm meaning that the printer used three times color a, four times color b, one time color h 
// then one time color a...

// Sometimes there are problems: lack of colors, technical malfunction and a "bad" control string is produced 
// e.g. aaaxbbbbyyhwawiwjjjwwm with letters not from a to m.

// You have to write a function printer_error which given a string will return the error rate of the printer 
// as a string representing a rational whose numerator is the number of errors and the denominator the length 
// of the control string. Don't reduce this fraction to a simpler expression.

// The string has a length greater or equal to one and contains only letters from ato z.

// Examples:
// s="aaabbbbhaijjjm"
// printer_error(s) => "0/14"

// s="aaaxbbbbyyhwawiwjjjwwm"
// printer_error(s) => "8/22"

#include <string>

class Printer {
 public:
  static std::string printerError(const std::string &s) {
    int num_errors = 0;

    for (auto c : s) {
      if (c - 'm' > 0) num_errors++;
    }
    
    return std::to_string(num_errors) + "/" + std::to_string(s.size());
  };
};

int main() {
  assert(Printer::printerError("aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbmmmmmmmmmmmmmmmmmmmxyz") == "3/56");
  assert(Printer::printerError("kkkwwwaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbmmmmmmmmmmmmmmmmmmmxyz") == "6/60");
  assert(Printer::printerError("kkkwwwaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbmmmmmmmmmmmmmmmmmmmxyzuuuuu") == "11/65");

  return 0;
}