I need to divide all natural numbers from 1 to n into three sets so that the sum of the numbers in each set is the same. If it can't, return -1 The output should be, for example n = 5:
2
1 4
2
2 3
1
5
I try to do this by my code:
n = int(input())
def divide_numbers(n):
if n * (n + 1) / 2 % 3 == 0:
numbers = [i for i in range(1, n+1)]
total_sum = sum(numbers)
set_sum = total_sum // 3
sets = [[], [], []]
for num in numbers:
if sum(sets[0]) + num <= set_sum and len(sets[0])<2:
sets[0].append(num)
elif sum(sets[1]) + num <= set_sum and len(sets[1])<2:
sets[1].append(num)
else:
sets[2].append(num)
return sets
else:
return -1
a = divide_numbers(n)
if a != -1:
first = a[0]
len_first = len(first)
second = a[1]
len_second = len(second)
thired = a[2]
len_thired = len(thired)
print(len_first)
print(*first)
print(" ")
print(len_second)
print(*second)
print(" ")
print(len_thired)
print(*thired)
else: print(a)
but the output is for n = 5:
2
1 2
1
3
2
4 5
I know that the condition that the sum of the numbers in the set must be equal is not met, how can I fix this?
