title: Find Sum Modulo K First N Natural Number 1
signature: function findSumModuloKFirstNNaturalNumber1($n, $k) {
test_code: <?php
  
  
  // SOLUTION CODE 
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  function validateSolution($actual, $expected){
      return serialize($actual) == serialize($expected);
  }
  
  function driver($n, $k, $expected){
      try{
        if (validateSolution(PLACEHOLDER_FN_NAME($n, $k), $expected)){
          return "PASSED";
        }
        return "FAILED";
      }
      catch (Exception $exception_obj) {
        return get_class($exception_obj);
      }
  }
  
  function main(){
      printf("TEST-0...%s\n",driver(
        40, 90, 
        2600));
      
      printf("TEST-1...%s\n",driver(
        46, 64, 
        2530));
      
      printf("TEST-2...%s\n",driver(
        97, 20, 
        1074));
      
      printf("TEST-3...%s\n",driver(
        63, 1, 
        0));
      
      printf("TEST-4...%s\n",driver(
        92, 52, 
        3166));
      
      printf("TEST-5...%s\n",driver(
        60, 35, 
        1345));
      
      printf("TEST-6...%s\n",driver(
        67, 40, 
        1684));
      
      printf("TEST-7...%s\n",driver(
        61, 62, 
        3751));
      
      printf("TEST-8...%s\n",driver(
        74, 61, 
        2311));
      
      printf("TEST-9...%s\n",driver(
        67, 41, 
        1691));
      
  }
  
  main();
  ?>
source_py: def find_sum_modulo_k_first_n_natural_number_1(N, K):
      ans = 0
      y = (N / K)
      x = (N % K)
      ans = ((((K * (K - 1)) / 2) * y) + ((x * (x + 1)) / 2))
      return int(ans)
source_cpp: int find_sum_modulo_k_first_n_natural_number_1(int N, int K) {
    int ans = 0;
    int y = N / K;
    int x = N % K;
    ans = ( K * ( K - 1 ) / 2 ) * y + ( x * ( x + 1 ) ) / 2;
    return ans;
  }