Syntax error Program to find minimum number of characters to be deleted to make A's before B's in Python

Program to find minimum number of characters to be deleted to make A's before B's in Python

Suppose we have a string s consisting only two letters A and B, we have to find the minimum number of letters that need to be deleted from s to get all occurrences of As before all occurrences of Bs.

So, if the input is like S = "AABAABB", then the output will be 1, as We can remove the last A to get AABBB

To solve this, we will follow these steps:

  • a_right := number of occurrences of "A" in s

  • b_left := 0

  • ans := a_right

  • for each index i and character c in s, do

    • if c is same as "A", then

      • a_right := a_right - 1

    • otherwise,

      • b_left := b_left + 1

    • ans := minimum of ans and a_right + b_left

  • return ans

Let us see the following implementation to get better understanding:

Example

 Live Demo

class Solution:
   def solve(self, s):
      a_right = s.count("A")
      b_left = 0

      ans = a_right
      for i, c in enumerate(s):
         if c == "A":
            a_right -= 1
         else:
            b_left += 1
         ans = min(ans, a_right + b_left)
      return ans

ob = Solution()
S = "AABAABB"
print(ob.solve(S))

Input

"AABAABB"

Output

1
Updated on: 2020-11-10T07:26:04+05:30

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