Swap For Longest Repeated Character Substring | OA LEVEL | TRICKY

https://leetcode.com/problems/swap-for-longest-repeated-character-substring/

You are given a string text. You can swap two of the characters in the text.
Return the length of the longest substring with repeated characters.

Example 1:
Input: text = "ababa"
Output: 3
Explanation: We can swap the first 'b' with the last 'a', or the last 'b' with the first 'a'. Then, the longest repeated character substring is "aaa" with length 3.

Example 2:
Input: text = "aaabaaa"
Output: 6
Explanation: Swap 'b' with the last 'a' (or the first 'a'), and we get longest repeated character substring "aaaaaa" with length 6.

Example 3:
Input: text = "aaaaa"
Output: 5
Explanation: No need to swap, longest repeated character substring is "aaaaa" with length is 5.


Constraints:
1 <= text.length <= 2 * 10^4
text consists of lowercase English characters only.

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class Solution {
public:
    int helper(string &s, char x){
        int n=s.size();
        int res=0;

        int countS=0; // number of characters in suffix
        for(auto c: s){
            countS+=(c==x);
        }

        int wS=0;
        int countP=0; // number of characters in prefix
        int mismatch=0;

        for(int wE=0;wE<n;wE++){
            mismatch+=(s[wE]!=x);
            countS-=(s[wE]==x);
            while(mismatch>1){
                countP+=(s[wS]==x);
                mismatch-=(s[wS]!=x);
                wS++;
            }
            if(countP>0 || countS>0 || mismatch==0){
                res=max(res,wE-wS+1);
            }
        }

        return res;
    }

    int maxRepOpt1(string text) {
        int res=1;
        for(int i=0;i<26;i++){
            res=max(res,helper(text,i+'a'));
        }
        return res;
    }
};