至少有K个重复字符的最长子串

Posted 2022-02-12 Alice_yufeng

class Solution 
    public int longestSubstring(String s, int k) 
        if (s.length() < k) return 0;
        HashMap<Character, Integer> counter = new HashMap();
        for (int i = 0; i < s.length(); i++) 
            counter.put(s.charAt(i), counter.getOrDefault(s.charAt(i), 0) + 1);
        
        for (char c : counter.keySet()) 
            if (counter.get(c) < k) 
                int res = 0;
                for (String t : s.split(String.valueOf(c))) 
                    res = Math.max(res, longestSubstring(t, k));
                
                return res;
            
        
        return s.length();