private static final String[] NUM_WORDS = {
        "", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten",
        "eleven", "twelve", "thirteen", "fourteen", "quarter", "sixteen", "seventeen",
        "eighteen", "nineteen", "twenty", "twenty one", "twenty two", "twenty three",
        "twenty four", "twenty five", "twenty six", "twenty seven", "twenty eight",
        "twenty nine", "half"
    };

    public static String timeInWords(int h, int m) {
        if(m == 0){
            //use o' clock
            String hour = NUM_WORDS[h];
            return hour + " o' clock";
        }
        if(m <= 30){
            //use past
            String minutes;
            if(m == 1)
                minutes = "one minute";
             else if(m == 15)
                minutes = "quarter";
            else if(m == 30)
                minutes = "half";
             else
                minutes = NUM_WORDS[m] + " minutes";
            
            String hour = NUM_WORDS[h];
            return minutes + " past " + hour;
        }
        else{
            //use to
            String minutes;
            if(60 - m == 1)
                minutes = "one minute";
             else if(60 - m == 15)
                minutes = "quarter";
             else
                minutes = NUM_WORDS[60 - m] + " minutes";
                
            String hour = NUM_WORDS[(h < 12) ? h + 1 : 1];
            return minutes + " to " + hour;
        }
    }