Count Binary Substrings

Problem

Count substrings of s that have an equal number of consecutive 0s and consecutive 1s, grouped together as in 0011 or 10.

Track the length of the current run and the previous run; each position contributes min(previous, current) valid substrings. Assume s contains only 0 and 1 characters.

Hint

Only boundaries between a run and the next run can produce valid substrings.

Test cases

case 1

in: ["00110011"]

expected: 6

case 2

in: ["10101"]

expected: 4

case 3

in: [""]

expected: 0

case 4

in: ["1"]

expected: 0

case 5

in: ["000111"]

expected: 3

Starter codePython

def count_binary_substrings(s):
    # Your code here
    pass

5 test cases · run your code against them in the editor