68. Text Justification

Hard
也是太messy的一道题了, discussion里面有一个post还是蛮有意思的，讨论这道题的意义：What does this question aim to teach?

今日最佳：
it teaches you in the real world. Programmers are always been ask to deal with dirty works.

class Solution {
    public List fullJustify(String[] words, int maxWidth) {
        List res = new ArrayList<>();
        if (words == null || words.length == 0){
            return res;
        }
        int index = 0;
        while (index < words.length){ 
            int curtLen = words[index].length();
            int last = index + 1;
            while (last < words.length){
                if (1 + words[last].length() + curtLen > maxWidth){
                    break;
                }
                curtLen += 1 + words[last].length();
                last++;
            }
            StringBuilder line = new StringBuilder();
            line.append(words[index]);
            int numGap = last - 1 - index;
            //if words[j - 1] is the last word or number of word is one in the line, left justify
            if (last == words.length || numGap == 0){
                for (int i = index + 1; i < last; i++){
                    line.append(" ");
                    line.append(words[i]);
                }
                for (int i = line.length(); i < maxWidth; i++){
                    line.append(" ");
                }
            } else {
                //middle justify
                //spacesPerGap是 extra spaces between words,计算curtLen时已算word之间本身的一个空格
                int spacesPerGap = (maxWidth - curtLen) / numGap;
                int remainSpaces = (maxWidth - curtLen) % numGap;
                for (int i = index + 1; i < last; i++){
                    for (int k = spacesPerGap; k > 0; k--){
                        line.append(" ");
                    }
                    if (remainSpaces > 0){
                        line.append(" ");
                        remainSpaces--;
                    }
                    line.append(" ");
                    line.append(words[i]);
                }
            }
            res.add(line.toString());
            index = last;
        }
        return res;
    }
}