public static String happyLadybugs(String b) {
        HashMap<Character, Integer> colors = new HashMap<>();
        int n = b.length();
        boolean contain_underscore = false;
        boolean same_color_adjacent = true;
        char prev = ' ';
        
        for(int i = 0; i < n; i++){
            char c = b.charAt(i);
            if(c == '_') contain_underscore = true;
         
            else{
              if (i > 0 && !contain_underscore && c != prev && colors.get(prev) <= 1)
                   same_color_adjacent = false; 
              prev = c;
                
                
              if(!colors.containsKey(c))
                    colors.put(c, 1);
              else
                    colors.replace(c, colors.get(c) + 1);  
              }
             
            }
        
        if(!contain_underscore && !same_color_adjacent)
            return "NO";
        
        for(Integer val:colors.values())
            if(val <= 1)
                return "NO";
        
        return "YES"; 
        
        }