title: Sum Series 23 45 67 89 Upto N Terms
signature: sumSeries23456789UptoNTerms(n) {
test_code: import 'dart:convert';
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  bool validateSolution(double actual, double expected){
      return (actual - expected).abs() < 1e-09;
  }
  
  String driver(n, double expected){
      try
      {
          if (validateSolution(PLACEHOLDER_FN_NAME(n), expected)){
              return "PASSED";
          }
          return "FAILED";
      }catch(exception_object){
          return exception_object.runtimeType.toString();
      }
  }
  
  int main() {
  
      print("TEST-0...${driver(
          49, 
          0.7803986631477524)
      }");
  
      print("TEST-1...${driver(
          4, 
          -0.16507936507936516)
      }");
  
      print("TEST-2...${driver(
          60, 
          -0.21050375120783382)
      }");
  
      print("TEST-3...${driver(
          90, 
          -0.21185466678122022)
      }");
  
      print("TEST-4...${driver(
          96, 
          -0.2120245854859959)
      }");
  
      print("TEST-5...${driver(
          29, 
          0.7770671416747363)
      }");
  
      print("TEST-6...${driver(
          86, 
          -0.21172836828074082)
      }");
  
      print("TEST-7...${driver(
          47, 
          0.780190394898247)
      }");
  
      print("TEST-8...${driver(
          77, 
          0.7821931668684383)
      }");
  
      print("TEST-9...${driver(
          87, 
          0.7825573460049735)
      }");
  
      return 0;
  }
source_py: def sum_series_23_45_67_89_upto_n_terms(n):
      i = 1
      res = 0.0
      sign = True
      while (n > 0):
          n = (n - 1)
          if sign:
              sign = False
              res = (res + ((i + 1) / (i + 2)))
              i = (i + 2)
          else:
              sign = True
              res = (res - ((i + 1) / (i + 2)))
              i = (i + 2)
      return res
source_cpp: double sum_series_23_45_67_89_upto_n_terms(int n) {
    int i = 1;
    double res = 0.0;
    bool sign = true;
    while ( n > 0 ) {
      n --;
      if ( sign ) {
        sign = ! sign;
        res = res + ( double ) ++ i / ++ i;
      }
      else {
        sign = ! sign;
        res = res - ( double ) ++ i / ++ i;
      }
    }
    return res;
  }