python leetcode 821. Shortest Distance to a Character

Given a string  S  and a character  C , return an array of integers representing the shortest distance from the character  C  in the string.
文字列内の指定した文字との最短距離を見つけます.
Example 1:

Input: S = "loveleetcode", C = 'e'
Output: [3, 2, 1, 0, 1, 0, 0, 1, 2, 2, 1, 0]

 
Note:

S  string length is in  [1, 10000].

C  is a single character, and guaranteed to be in string  S .

All letters in  S  and  C  are lowercase.

class Solution:
    def shortestToChar(self, S, C):
        """
        :type S: str
        :type C: str
        :rtype: List[int]
        """
        index_nums = []
        for i, letter in enumerate(S):
            if letter == C:
                index_nums.append(i)
                
        ans = []
        for j, word in enumerate(S):
            distance = [abs(j - index_num) for index_num in index_nums]
            ans.append(min(distance))
            
        return ans