答案：

    public String countAndSay(int n) {
        StringBuilder stringBuilder = new StringBuilder("1");
        StringBuilder tempString = new StringBuilder();
        for (int i = 1; i < n; i++) {
            tempString.delete(0, tempString.length());
            char curDigit = stringBuilder.charAt(0);
            int digitCount = 1;
            for (int j = 1; j < stringBuilder.length(); j++) {
                //统计当前数字的个数
                if (curDigit == stringBuilder.charAt(j)) {
                    digitCount++;
                } else {
                    //变到另一个数字要重新统计
                    tempString.append(digitCount).append(curDigit);
                    curDigit = stringBuilder.charAt(j);
                    digitCount = 1;
                }
            }
            tempString.append(digitCount).append(curDigit);

            stringBuilder.delete(0, stringBuilder.length());
            stringBuilder.append(tempString);
        }
        return stringBuilder.toString();
    }