New to Python, i am Missing an Output. goal is to find all possible outcomes from a list that sums to Zero

Problem: From a given list, i should return all possible outcomes that give a sum of 0
for a list [-1,0,1,2,-1,-4] the output should be [[-1,-1,2],[-1,0,1]]

The problem is it’s not showing all possible outcomes.

Code:

nums = [-1,0,1,2,-1,-4]
def three_sum():
  lst=[]
  for i in nums:             #take 3 variables
    for j in nums:
      for k in nums:
        if (nums.index(i) != nums.index(j)) and (nums.index(i) != nums.index(k)) and (nums.index(j) != nums.index(k)): 
          if i+j+k==0:
            tmp_lst=[i,j,k]
            tmp_lst.sort()
            lst.append(tmp_lst)
  for m in lst:
    while lst.count(m)>1:
      lst.remove(m)
      lst.sort()
  return lst

The expected output should be [[-1,-1,2],[-1,0,1]] but i get [[-1, 0, 1]]

>Solution :

The problem is when you check (nums.index(i) != nums.index(j)) and (nums.index(i) != nums.index(k)) and (nums.index(j) != nums.index(k)), if you have two equal numbers in the list (like two -1) then nums.index will return the index of the first one and you will discard that combination.

To solve this I changed your i, j and k to be the indexes and force them to not be equal directly in the range function.

nums = [-1, 0, 1, 2, -1, -4]


def three_sum(nums):
    lst = []
    for i in range(len(nums)):
        for j in range(i + 1, len(nums)):
            for k in range(j + 1, len(nums)):
                n1, n2, n3 = nums[i], nums[j], nums[k]
                if n1 + n2 + n3 == 0:
                    tmp_lst = [n1, n2, n3]
                    tmp_lst.sort()
                    lst.append(tmp_lst)

    # remove possible duplicates
    for m in lst:
        while lst.count(m) > 1:
            lst.remove(m)
            lst.sort()

    return lst


print(three_sum(nums))