Today I have done leetcode's July LeetCoding Challenge with cpp.

July LeetCoding Challenge 30

Description

Minimum Deletions to Make String Balanced

You are given a string s consisting only of characters 'a' and 'b'​​​​.

You can delete any number of characters in s to make s balanced. s is balanced if there is no pair of indices (i,j) such that i < j and s[i] = 'b' and s[j]= 'a'.

Return the minimum number of deletions needed to make s balanced.

Example 1:

Input: s = "aababbab"
Output: 2
Explanation: You can either:
Delete the characters at 0-indexed positions 2 and 6 ("aababbab" -> "aaabbb"), or
Delete the characters at 0-indexed positions 3 and 6 ("aababbab" -> "aabbbb").

Example 2:

Input: s = "bbaaaaabb"
Output: 2
Explanation: The only solution is to delete the first two characters.

Constraints:

• 1 <= s.length <= 105
• s[i] is 'a' or 'b'​​.

Solution

class Solution {
public:
  int minimumDeletions(string s) {
    int as = 0;
    int bs = 0;
    for(auto c : s) {
      if(c == 'a') {
        as += 1;
      }
    }
    int answer = as;
    for(auto c : s) {
      if(c == 'a') {
        as -= 1;
      } else {
        bs += 1;
      }
      answer = min(answer, as + bs);
    }
    return answer;
  }
};