68. Text Justification

class Solution {
    public List<String> fullJustify(String[] words, int maxWidth) {
        List<String> res=new ArrayList<String>();
        int idx=0;
        while(idx<words.length)
        {
            int curlen=0;
            int i=idx;
            while(i<words.length&&curlen+words[i].length()<=maxWidth)
            {
                curlen+=words[i].length()+1;
                i++;
            }
            curlen--;
            
            StringBuilder sb=new StringBuilder();
            if(i==words.length||i==idx+1)
            {
                for(int k=idx;k<i-1;k++)
                    sb.append(words[k]+" ");
                sb.append(words[i-1]);
                for(int k=sb.length();k<maxWidth;k++)
                    sb.append(" ");
                res.add(sb.toString());
            }
            else
            {
                int space=(maxWidth-curlen)/(i-idx-1);
                int extra=(maxWidth-curlen)%(i-idx-1);
                String sp="";
                for(int k=0;k<space;k++)
                    sp+=" ";
                for(int k=idx;k<i-1;k++)
                {
                    sb.append(words[k]+" "+sp);
                    if(extra>0)
                    {
                        sb.append(" ");
                        extra--;
                    }
                }
                sb.append(words[i-1]);
                res.add(sb.toString());
            }
            idx=i;
        }
        return res;
    }
}