BinarySearchIO - A unique string

'''
Given a string s, determine whether it has all unique characters.
Example 1
Input
s = "abcde"
Output
True
'''

def solve(s):
    unique = list()
    for i in range(len(s)):
        if s[i] not in unique:
            unique.append(s[i])
    # Create a dictionary
    dictionary = dict()
    for char in unique:
        dictionary[char] = 0
    for i in range(len(s)):
        for j in range(len(unique)):
            if s[i] == unique[j]:
                dictionary[s[i]] += 1
    # Now, we have the dictionary and the appearance of each unique letter
    print(dictionary)
    for key in dictionary:
        if dictionary[key] != 1:
            return False
    return True


# MAIN FUNCTION
print(solve("abcde"))
print(solve("abcdef"))
print(solve("abcdeeeeea"))
print(solve("abcdeAAd"))