#-------------------------------------------------------------------------------
#  Sum.py
#  Add up the numbers from 1 to n in four different ways
#-------------------------------------------------------------------------------


# function main() -------------------------------------------------------------
def main():
   
   n = 10
   sum1 = sum2 = sum3 = sum4 = 0
   print()

   # using a for loop
   for i in range(1,n+1):
      sum1 += i
   # end for
   print('i =', i)
   print('sum1 =', sum1)
   print()

   # using a while loop
   j = 1
   while j <= n:
      sum2 += j
      j += 1
   # end while
   print('j =', j)
   print('sum2 =', sum2)
   print()

   # using a well known formula:  n(n+1)/2
   sum3 = n*(n+1)//2
   print('sum3 =', sum3)
   print()

   # the least efficient way, using a double for loop
   for i in range(1, n+1):
      for j in range(1, i+1):
         sum4 += 1
      # end for
   # end for
   print('i = ', i, ", j = ", j, sep='')
   print('sum4 =', sum4)
   print()

# end main() ------------------------------------------------------------------


# closing conditional ---------------------------------------------------------
if __name__=='__main__':

   main()

# end