Change Minimum Characters to Satisfy One of Three Conditions LeetCode solution in Python

1
class Solution:
2
    def minCharacters(self, a: str, b: str) -> int:
3
        pa, pb = [0] * 26, [0] * 26
4
        for x in a:
5
            pa[ord(x) - 97] += 1
6
        for x in b:
7
            pb[ord(x) - 97] += 1
8

9
        ans = len(a) - max(pa) + len(b) - max(pb)  # condition 3
10
        for i in range(25):
11
            pa[i + 1] += pa[i]
12
            pb[i + 1] += pb[i]
13
            ans = min(ans, pa[i] + len(b) - pb[i])  # condition 2
14
            ans = min(ans, len(a) - pa[i] + pb[i])  # condition 1
15
        return ans