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

n = 100
sum1 = sum2 = sum3 = sum4 = 0
print()

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

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

# using a well known formula:  n(n+1)/2
sum3 = n*(n+1)//2
print('sum3 = '+str(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 = '+str(i)+", j = "+str(j))
print('sum4 = '+str(sum4))
print()