'''
The appeal of a string is the number of distinct characters found in the string.

For example, the appeal of "abbca" is 3 because it has 3 distinct characters: 'a', 'b', and 'c'.
Given a string s, return the total appeal of all of its substrings.

A substring is a contiguous sequence of characters within a string.

 

Example 1:

Input: s = "abbca"
Output: 28
Explanation: The following are the substrings of "abbca":
- Substrings of length 1: "a", "b", "b", "c", "a" have an appeal of 1, 1, 1, 1, and 1 respectively. The sum is 5.
- Substrings of length 2: "ab", "bb", "bc", "ca" have an appeal of 2, 1, 2, and 2 respectively. The sum is 7.
- Substrings of length 3: "abb", "bbc", "bca" have an appeal of 2, 2, and 3 respectively. The sum is 7.
- Substrings of length 4: "abbc", "bbca" have an appeal of 3 and 3 respectively. The sum is 6.
- Substrings of length 5: "abbca" has an appeal of 3. The sum is 3.
The total sum is 5 + 7 + 7 + 6 + 3 = 28.
Example 2:

Input: s = "code"
Output: 20
Explanation: The following are the substrings of "code":
- Substrings of length 1: "c", "o", "d", "e" have an appeal of 1, 1, 1, and 1 respectively. The sum is 4.
- Substrings of length 2: "co", "od", "de" have an appeal of 2, 2, and 2 respectively. The sum is 6.
- Substrings of length 3: "cod", "ode" have an appeal of 3 and 3 respectively. The sum is 6.
- Substrings of length 4: "code" has an appeal of 4. The sum is 4.
The total sum is 4 + 6 + 6 + 4 = 20.
 

Constraints:

1 <= s.length <= 105
s consists of lowercase English letters.
'''
import unittest

from typing import *

class Solution:
    def appealSum(self, s: str) -> int:
        maps = {}
        prev = 0
        sum_v = 0
        for i in range(len(s)):
            prev = prev + i - maps.get(s[i], -1)
            sum_v += prev
            maps[s[i]] = i
        return sum_v
        
        
        
class TestSolution(unittest.TestCase):

    def test_case(self):
        examples = (
            (("abbca",),28),
        )
        for first, second in examples:
            self.assert_function(first, second)

    def assert_function(self, first, second):
        self.assertEqual(Solution().appealSum(*first), second,
                         msg="first: {}; second: {}".format(first, second))


unittest.main()
