Divide a String Into Groups of Size k

把一个字符串分割成k组, 如果不满k,就用fill字符补.

class Solution {
    public String[] divideString(String s, int k, char fill) {
        List<String> list = new ArrayList<>();
        int n = s.length();
        StringBuffer sb = new StringBuffer(s);
        int m = n % k == 0 ? 0 : k - (n%k);
        for(int i = 0; i < m; i++)
            sb.append(fill);
        String str = sb.toString();
        for(int i = 0; i < str.length(); i+=k){
            list.add(str.substring(i, i + k));
        }
        String[] strs = new String[list.size()];
        for(int i = 0; i < list.size(); i++)
            strs[i] = list.get(i);
        return strs;
    }
}