Count Binary Substrings LeetCode solution in Python

1
# Runtime: 133 ms (Top 63.3%) | Memory: 16.65 MB (Top 94.0%)
2

3

4
class Solution:
5
    def countBinarySubstrings(self, s: str) -> int:
6

7
        # previous continuous occurrence, current continuous occurrence
8
        pre_cont_occ, cur_cont_occ = 0, 1
9

10
        # counter for binary substrings with equal 0s and 1s
11
        counter = 0
12

13
        # scan each character pair in s
14
        for idx in range(1, len(s)):
15

16
            if s[idx] == s[idx - 1]:
17

18
                # update current continuous occurrence
19
                cur_cont_occ += 1
20

21
            else:
22
                # update counter of binary substrings between prevous character group and current character group
23
                counter += min(pre_cont_occ, cur_cont_occ)
24

25
                # update previous as current's continuous occurrence
26
                pre_cont_occ = cur_cont_occ
27

28
                # reset current continuous occurrence to 1
29
                cur_cont_occ = 1
30

31
        # update for last time
32
        counter += min(pre_cont_occ, cur_cont_occ)
33

34
        return counter