Creating a dictionary from 2 lists by storing multiple values with repeated keys

There are 2 lists. What I am trying to do is to find the occurrence of first list elements and will hold the values of second list for a key in first list and in the end, it will become dictionary holding specific keys from list 1 and values from list 2

Input:

list1 = ['A', 'A', 'B', 'B', 'C', 'D']
list2 = [1, 2, 3, 4, 5, 6]

Expected Output:

{'A': [1, 2], 'B': [3, 4], 'C': [5], 'D':[6]}

Current Output:

{'A': [1, 2], 'B': [4], 'C': []}

What I tried so far,

values = [list2[0]]
key = list1[0]
dic = {}
for i in range(1, len(list1)):
    if list1[i] == list1[i - 1]:
        values.append(list2[i])
    elif list1[i] != list1[i - 1]:
        dic.update({key: values})
        values = []
        key = list1[i]
print(dic)

List 1 and List 2 are always equal in length and sorted

>Solution :

You can use dict.setdefault to initialize each distinct key with a new list to append values to:

output = {}
for key, value in zip(list1, list2):
    output.setdefault(key, []).append(value)

output would become:

{'A': [1, 2], 'B': [3, 4], 'C': [5], 'D': [6]}

Demo: https://replit.com/@blhsing/InstructiveNoxiousCollaborativesoftware