10033. Find Longest Special Substring That Occurs Thrice II

You are given a string s that consists of lowercase English letters.

A string is called special if it is made up of only a single character. For example, the string "abc" is not special, whereas the strings "ddd", "zz", and "f" are special.

Return the length of the longest special substring of s which occurs at least thrice, or -1 if no special substring occurs at least thrice.

A substring is a contiguous non-empty sequence of characters within a string.

c++

class Solution {
public:
    int maximumLength(string s) {
        unordered_map<int, unordered_map<int, int>> mp;
        int l = 0, r = 0, n = s.length();
        while(r < n) {
            while(r < n and s[l] == s[r]) r++;
            mp[s[l]-'a'][r-l] += 1;
            l = r;
        }
        int res = -1;
        for(auto& [_, mmp] : mp) {
            for(auto& [k,v] : mmp) {
                if(k >= 3) {
                    res = max(res, k - 2);
                }
                if(v >= 3) {
                    res = max(res, k);
                }
                if(v >= 2) {
                    res = max(res, k - 1);
                }
                if(v == 1) {
                    if(mmp.count(k - 1)) res = max(res, k - 1);
                }
            }
        }
        if(res == 0) return -1;
        return res;
    }
};

c++

class Solution {
public:
    int maximumLength(string s) {
        unordered_map<int, unordered_map<int, int>> mp;
        int l = 0, r = 0, n = s.length();
        int res = -1;
        while(r < n) {
            while(r < n and s[l] == s[r]) r++;
            int len = r - l;
            for(int i = 1; i <= 3 and len > 0; i++, len--) {
                mp[s[l]-'a'][len] += i;
                if(mp[s[l]-'a'][len] >= 3) res = max(res, len);
            }
            l = r;
        }
        return res;
    }
};