Check If every group of a is followed by a group of b of same length in Python

Suppose we have a lowercase string s with only two characters a and b. We have to check whether every group of consecutive a's is followed by group of consecutive b's of equal length.

So, if the input is like s = "abaaabbbaabbaabbab", then the output will be True, as all groups are (ab), (aaabbb), (aabb), (aabb), (ab).

To solve this, we will follow these steps −

• a_count := 0, string_len := size of s
• i := 0
• while i < string_len, do
  • while i < string_len and s[i] is 'a', do
    • a_count := a_count + 1
    • i := i + 1
  • while i < string_len and s[i] is 'b', do
    • a_count := a_count - 1
    • i := i + 1
  • if a_count is not 0, then
    • return False
• return True

Example

Let us see the following implementation to get better understanding −

 Live Demo

def solve(s):
   a_count = 0
   string_len = len(s)
   i = 0
   while i < string_len:
      while i < string_len and s[i] == 'a':
         a_count += 1
         i += 1
      while i < string_len and s[i] == 'b':
         a_count -= 1
         i += 1
      if a_count != 0:
         return False
   return True
s = "abaaabbbaabbaabbab"
print(solve(s))

Input

"abaaabbbaabbaabbab"

Output

True