title: Divisibility By 7
signature: function divisibilityBy7($num) {
test_code: <?php
  
  
  // SOLUTION CODE 
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  function validateSolution($actual, $expected){
      return serialize($actual) == serialize($expected);
  }
  
  function driver($num, $expected){
      try{
        if (validateSolution(PLACEHOLDER_FN_NAME($num), $expected)){
          return "PASSED";
        }
        return "FAILED";
      }
      catch (Exception $exception_obj) {
        return get_class($exception_obj);
      }
  }
  
  function main(){
      printf("TEST-0...%s\n",driver(
        0, 
        true));
      
      printf("TEST-1...%s\n",driver(
        -21, 
        false));
      
      printf("TEST-2...%s\n",driver(
        7, 
        true));
      
      printf("TEST-3...%s\n",driver(
        63, 
        false));
      
      printf("TEST-4...%s\n",driver(
        84, 
        false));
      
      printf("TEST-5...%s\n",driver(
        73, 
        false));
      
      printf("TEST-6...%s\n",driver(
        81, 
        false));
      
      printf("TEST-7...%s\n",driver(
        -10, 
        false));
      
      printf("TEST-8...%s\n",driver(
        47, 
        false));
      
      printf("TEST-9...%s\n",driver(
        23, 
        false));
      
  }
  
  main();
  ?>
source_py: def divisibility_by_7(num):
      if (num < 0):
          return divisibility_by_7((- num))
      if ((num == 0) or (num == 7)):
          return True
      if (num < 10):
          return False
      return divisibility_by_7(((num / 10) - (2 * (num - ((num / 10) * 10)))))
source_cpp: int divisibility_by_7(int num) {
    if ( num < 0 ) return divisibility_by_7 ( - num );
    if ( num == 0 || num == 7 ) return 1;
    if ( num < 10 ) return 0;
    return divisibility_by_7 ( num / 10 - 2 * ( num - num / 10 * 10 ) );
  }